Kumhos vs Hoosiers IMHO
11-12-2007, 03:35 PM
#1
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St. Jude Donor '05-'08
Kumhos vs Hoosiers IMHO
Well I tested both this year - Kumhos V710s and Hoosiers R6 (I also ran the V700 for one session in the rain, but that is a different story).
First I started with the Kumhos - I had them last year and continued to use them for the beginning of this year. Very predictable tire. They start out great right from the start, but seem to get greasy around the end of a 30 min session. The feedback from the tire not only through noise but also through the steering I found to be very consistant.
I then switched over to the Hoosiers based on what I learned here. Right out of the box they are real slippery and take some time to warm up, but once they do boy do they grab and they last the full session. The Hoosiers still made noise when you pushed them but the feedback in the steering wasnt there. More like you had to trust that the tire was there because it was effortless to go through the turns.
Personally I did not like the Hoosiers for 25 min HPDE sessions. Too long to heat up and I like the feedback from the Kumhos (it makes me feel more comfortable). For an Advance day with unlimited track then the Hoosiers are better. They take longer to heat, but who cares when you get 45+ min sessions.
I am going to try the A6 because I have heard the heat up quicker. They might not last as many days, but thats ok if they are quicker.
First I started with the Kumhos - I had them last year and continued to use them for the beginning of this year. Very predictable tire. They start out great right from the start, but seem to get greasy around the end of a 30 min session. The feedback from the tire not only through noise but also through the steering I found to be very consistant.
I then switched over to the Hoosiers based on what I learned here. Right out of the box they are real slippery and take some time to warm up, but once they do boy do they grab and they last the full session. The Hoosiers still made noise when you pushed them but the feedback in the steering wasnt there. More like you had to trust that the tire was there because it was effortless to go through the turns.
Personally I did not like the Hoosiers for 25 min HPDE sessions. Too long to heat up and I like the feedback from the Kumhos (it makes me feel more comfortable). For an Advance day with unlimited track then the Hoosiers are better. They take longer to heat, but who cares when you get 45+ min sessions.
I am going to try the A6 because I have heard the heat up quicker. They might not last as many days, but thats ok if they are quicker.
11-12-2007, 04:20 PM
#3
Melting Slicks
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I used the 710 exclusively for 2 years, but once Hoosier came out the the new A6/R6 design, I dumped the Kumhos in a hearbeat.
If you are looking for maximum grip, the only tire to use is the A6. It will give you 80% grip from cold and be completely ready to rumble at 100% by the end of your first lap.
Ultimate grip is much higher in the A6 than the 710. It is VERY IMPORTANT that you run the A6/R6 at the right pressures. They are low pressure tires (at least when compared to the old Hoosiers).
I run my A6/R6 at 30 PSI front and 26 PSI rear (HOT TEMPERATURES). This usually requires cold pressures of about 26F, 22R; but this may be different depending on the peak temps you get at your track.
I have run the A6/R6 in both my C5Z and my C6Z. Both car behaved impeccably with them on.
Last data point: Most SCCA T-1 racers are running Hoosier A6s. The T-1 race at the Topeka runoffs had C6 coupes on A6s in 1st and 2nd places.
YMMV, but for my money, Hoosier is the tire.
If you are looking for maximum grip, the only tire to use is the A6. It will give you 80% grip from cold and be completely ready to rumble at 100% by the end of your first lap.
Ultimate grip is much higher in the A6 than the 710. It is VERY IMPORTANT that you run the A6/R6 at the right pressures. They are low pressure tires (at least when compared to the old Hoosiers).
I run my A6/R6 at 30 PSI front and 26 PSI rear (HOT TEMPERATURES). This usually requires cold pressures of about 26F, 22R; but this may be different depending on the peak temps you get at your track.
I have run the A6/R6 in both my C5Z and my C6Z. Both car behaved impeccably with them on.
Last data point: Most SCCA T-1 racers are running Hoosier A6s. The T-1 race at the Topeka runoffs had C6 coupes on A6s in 1st and 2nd places.
YMMV, but for my money, Hoosier is the tire.
11-12-2007, 04:22 PM
#4
Melting Slicks
I don't know about A6s on the track. I lightly corded the outside of one front at 39 laps AutoXing. Most of those laps were at a very grippy concrete venue, but still 39 AutoX laps is nothing. And I'm running -2.8 Camber so I don't think that was the issue. I should have had the tires flipped around 30-35 laps and I think I would ahve been lucky to get 70 total. I'm giving up on the A6 at over $1500/set 70 laps "if I'm lucky" just isn't going to cut it. I'd almost be scared to try a 25 minute HPDE session on A6s not knowing how quick they'd cord out.
-TJ
-TJ
11-12-2007, 04:30 PM
#5
Melting Slicks
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I don't know about A6s on the track. I lightly corded the outside of one front at 39 laps AutoXing. Most of those laps were at a very grippy concrete venue, but still 39 AutoX laps is nothing. And I'm running -2.8 Camber so I don't think that was the issue. I should have had the tires flipped around 30-35 laps and I think I would ahve been lucky to get 70 total. I'm giving up on the A6 at over $1500/set 70 laps "if I'm lucky" just isn't going to cut it. I'd almost be scared to try a 25 minute HPDE session on A6s not knowing how quick they'd cord out.
-TJ
-TJ
I never flipped them or otherwise disturbed them on the rims.
What pressures are you running?
What are your full alignment specs?
There is something not cool with your results and we need to pin it down for you.
A set of A6s shoulod survive several days of HPDE use while giving you unparalleled grip. They last a complete T-1 race with plenty of tread left over.
Feel free to PM me if you want to discuss this further.
11-12-2007, 04:38 PM
#6
"AlohaC5" Senior Member
I ran the Kumho V710 (shaved) with good results; however, since moving to the Hoosier R6 - I'll never use another tire. Simply awesome performance - grip, handing, wear, predictability, etc. I wouldn't think the A6 would be recommended for road course work since its a softer compount that would wear and cord quickly.
Last edited by Gray Ghost GS; 11-13-2007 at 05:31 PM.
11-12-2007, 05:40 PM
#7
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St. Jude Donor '05-'08
thanks Frank for your response. I was running mine higher hot temps. before i switch over to something new I will try with your recommended hot temps and see what happens.
as far as durability the hoosiers and kumhos have both lasted a long time which is good for us unsponsored HPDE guys.
as far as durability the hoosiers and kumhos have both lasted a long time which is good for us unsponsored HPDE guys.
11-12-2007, 05:50 PM
#8
Team Owner
thanks Frank for your response. I was running mine higher hot temps. before i switch over to something new I will try with your recommended hot temps and see what happens.
as far as durability the hoosiers and kumhos have both lasted a long time which is good for us unsponsored HPDE guys.
as far as durability the hoosiers and kumhos have both lasted a long time which is good for us unsponsored HPDE guys.
I am ending in 40-41 range and starting at 33/32. They feel ready after one lap.
There was a question on the C6Z secton also. I could never run low pressures they felt like they were coming off the rim when I tried GY scrubs low when I first got them. If I ran Hoosiers low I would destroy the shoulders real fast. I found the Hoosiers as fast or even faster than the GY scrubs.
Last edited by John Shiels; 11-12-2007 at 05:59 PM.
11-12-2007, 05:55 PM
#9
Team Owner
--------------------------------------------------------------------------------
cars over 3,000 is me
http://www.hoosiertire.com/rrtire.htm
TIRE CARE TIPS
FOR R6 & A6 TIRES
(Download Printable Version)
The R6 and A6 have been developed to improve wear and consistency without any sacrifice of performance. In many cases, the performance will even improve over previous models. The new tire models are an evolution in the continuing effort to provide the best tire for racers.
- Tire Break-In Procedure
- Tire Temperature Recommendations
- Chassis Setup Recommendations
- Tire Pressure Recommendations
- Things to Consider
Tire Break-In Procedure
Proper break-in will not affect initial performance but will increase the competitive life of the tire.
The procedure can be broken down into phases.
1st phase: The initial run
2nd phase: The length of the time the tire is allowed to "cure"
The Initial Run Heat Cycle
R6 Roadrace
The first laps for the tire are critical for setting up the durability and competitive life. The first session should consist of no more than 10-15 minutes of running. The early part of the session should be run at an easy pace, with the speed gradually increased until the end of the session. The final lap should be run at the fastest possible speed. The intent is to achieve maximum tire temp on the last lap. At this point the car should be brought in and the tires allowed to cool at a normal rate.
During the initial run-in process, the inflation pressure should be 3-5 psi higher than you would normally use. The best progression would have the driver taking 4-7 laps to accomplish this break-in. Each lap should be approximately 7-10 seconds a lap faster than the previous lap. The goal is to have the tire temp as high as possible on the last lap without "shocking" the tire during the warm up laps. In essence, no wheelspin, late braking, or sliding. The last lap should be at, or very close, the maximum possible.
A6 Autocross
For autocrossing, the A6 does not need the same break in procedure as the R6. The A6 needs a minimal scuff-in session before the first autocross run. This “session” can comprise of simply driving around the event site at minimal speeds on the A6 set of tires. By scrubbing off the newness of the tread (no or minimal shininess remaining) prior to your first competitive run, the A6 tires will be more consistent in handling, grip and responsiveness on the first run. If this is not completed, running on un-scuffed A6 tires on your first run may result in the tires not gripping properly, or feeling like they “skate” over the course surface. You are welcome to run 3 – 5 psi higher when scuffing in a new set of A6’s, but be sure to reset them to the correct operating pressures before your first autocross run. As you compile autocross runs on your new A6’s, they should become more consistent in run times.
"Cure" Time
After completing the initial run phase, the length of time the tire is allowed to set is possibly more important. The barest minimum for this process to be beneficial is 24 hours. (Not "the next day"). Any less than this is a waste of time. The best situation would allow a week before using the tire again.
Proper tire management is a difficult process. To accomplish this almost always requires a second set of wheels. The payoff is greatly increased competitive tire life.
Following the recommended break-in procedure will require a lot of planning to make it work. The benefits to doing it right include greatly increased tire life as well as consistent performance and durability under stress. Please make an effort to educate your team on the importance of this. It can save you a lot of money.
Tire Temperature Recommendations
For best performance the expected temperature range will vary from track to track. Generally, optimum traction will be generated when the pit lane temps show 180-200 degrees for the R6 in Roadrace applications, and 140-150 degrees for the A6 in an Autocross application.
Note: Use of static infra-red pyrometers is an inaccurate method to monitor tire temps.
Chassis Setup Recommendations
For optimum performance the Hoosier P-Metric radial tires require about 3 degrees of camber. There will be a trade off in maximum performance to maximize wear. Generally, 1/2 degrees less than optimum will result in the best compromise for wear and speed. Less than 2.5 degrees can result in excessive wear on the shoulder junction.
The Hoosier tires typically offer better performance with spring/shock rates higher than previous brands you may have run.
Tire Pressure Recommendations For Competition
Traditionally, Hoosier tires have often required higher pressures than other brands. This has changed with the A6/R6.
Roadrace/track applications
Vehicle size
Recommended Hot Pressure
Cold Pressure
1800-2200 lbs.
34-37+
26-31
2200-2600 lbs.
35-38+
27-32
2600-3000 lbs.
37-41+
27-32
over 3000 lbs.
38-43+
27-33
+Higher pressures will improve the performance capability but will require a more sensitive feel to take advantage of the increase.
One characteristic of the tires is the tendency to "skate" initially (when inflation pressures are correct). It is important to resist lowering the pressure to attempt to eliminate this feeling. Dropping the pressure too far may improve the "feel" of the tire however it will also lower the performance and increase the wear rate.
Autocross applications
For autocross applications, your starting pressure for the first run should be within 1-2 psi of the recommended hot pressures shown above. After the first run and each subsequent run, keep resetting the pressures back to your target hot pressures before taking the next run. This way your tires are at the proper pressure during the bulk of every run you take.
The above chart is a general recommendation which is intended for a standard configuration vehicle (i.e. front engine, rear wheel drive). Factors which can radically affect your pressure set up would include front wheel drive, independent rear suspension, rear engine, McPherson vs. control arm front suspension.
Front Wheel Drive
Vehicles configured with FWD are probably the most difficult application for a tire setup. The combination of steering, braking and accelerating on the front tires, combined with higher corner weights for the front positions produce a harsh environment for the tire. These vehicles will typically have a strut type of suspension which limits camber gain. All these factors result in conditions which require the tire do more work than a simple chart for pressures can accommodate.
In severe cases front tire pressures for FWD vehicles can run in the 48-52 psi (hot). In cases where the tire size is limited to a relatively small tire, the required pressure can run even higher. The front to rear pressure differential on FWD cars can have extreme ranges of inflation, depending on the driver preference, suspension tuning, and track configuration.
Independent rear suspension
With IRS and proper geometry up front, tire pressures can be reduced from the recommendations listed above. When there is adequate camber gain and good roll control, the Hoosier radial tire will perform very well at the reduced air pressure. This results in a bigger "sweet spot" and easier control at the limit.
When tuning at reduced pressures use the following formula to determine the minimum safe pressure: Divide the total vehicle weight, including fuel and driver, by 100 to arrive at the minimum safe pressure. Example: Your car weighs 2750 lbs. as raced. The minimum safe (cold) pressure is 27.5 psi.
Extreme care should be taken when tuning at reduced pressure. Tire damage can occur that is not visible to external inspection.
Vehicles equipped with independent rear suspension (IRS) have a distinct advantage over non-IRS cars when using radial tires. This is true for two reasons. First, it is possible to setup some amount of static negative camber on IRS suspensions, if needed. Second, the IRS geometry can provide the proper camber gain to achieve the dynamic camber needed for a radial tire. This is a great benefit because it then becomes possible to better address front tire grip when the rear of the car can be optimized closer to the tire's potential.
THINGS TO CONSIDER
These tires are molded to their designed tread depth. They do not require shaving to be prepared for competition use.
Due to extremely light construction, Hoosier tires have a much lower polar moment than other radial tires. This translates to a very low rotational mass, which is a good thing for performance applications. The down side to this feature is that the tires do not resist "spikes" in braking force as well as a heavier tire might. As a result, there is a tendency for drivers to "flatspot" a tire the first time really getting to the limit. Vehicles equipped with ABS will benefit from its use. If you do not use ABS it is recommended that you make an effort to minimize stabbing the brakes until you have some experience with the feel of the tire under hard braking.
The light construction also provides less protection from impact damage and punctures. Off course excursions or running over debris on the track will likely result in tire damage.
The tires are not directional. Once some wear has occurred it may be desirable to flip the tire on the wheel in order to even out the wear and maximize tire life.
Wheel Widths
Wheel width dramatically affects wear and performance of the Hoosier P-Metric radial tires.
There is about a one inch window of optimum width. The trick is to figure out that window. A good rule of thumb to use for determining proper width is to use the tread width of the tire. Measure the tread width. Plus or minus 1/2 inch from the tread dimension will indicate the proper rim sizing. It is possible to use narrower wheels, but at a sacrifice to shoulder wear and cornering power.
"Measured" rim vs. "Recommended" rim
In our printed product catalog and on our website tire specifications you will see two columns of information regarding rim dimensions. In most cases, the "measured rim" and the "recommended rim" will be the same. However in the case of DOT tires, the information may appear contradictory.
The reason for the differences lies in the Department of Transportation requirements for publishing tire dimensions on any tire that carries a DOT certification. Each tire size has a specific rim that must be used when taking measurements for tire comparison. This is intended to allow consumers a consistent way to compare tire sizes between brands.
With respect to the Hoosier P-Metric line, the recommended rim size will typically be wider than the DOT standardized wheel.
The fact that a tire will "fit" on a rim is not an indication that it will work effectively in that condition. Radial tires are extremely sensitive to wheel widths. The performance characteristics of the tire can change significantly within the recommended range of application. Mounting a tire on a rim that is outside of the recommendation is not a good idea.
Driving Style/Braking
Driving style has also shown to significantly effect tire wear. Drivers who achieve their speed by "tossing" the car run the risk of increased tire wear. Radial tires develop their highest cornering power at relatively low slip angles. Smooth, tidy driving yields faster lap times and better tire wear.
The braking feel of the Hoosier R6 tire is very vague at the threshold. This is particularly true for "sticker" tires. Drivers need to develop a sensitivity for the limits under braking. This takes time and practice. Failure to apply this will result in flatspotted tires.
Particular care needs to be taken when selecting brake pad compounds. It is possible to have a pad that is too aggressive. This will make it very difficult to develop good braking fell for threshold braking.
Rain Tires
The Hoosier D.O.T. Radial tires are extremely good in dry conditions, however they do not make very good wet weather tires. Having dedicated rain tires available will be necessary for your team to be properly prepared. Hoosier makes a D.O.T. approved bias-ply tire called a "Dirt Stocker" that has been proven to be far superior to any competitors tire as long as it is a steady "wet" condition. Check with your Hoosier representative for size availability.
Hoosier Racing Tire also offers a D.O.T. Radial Wet tire. This tire has a molded tread of symmetrical design. Check the product catalog for the available sizes. The compound for these tires is intended for wet weather use only.
Hoosier also offers a non-D.O.T. radial rain tire based directly on the P-Metric R6 tire. The tread depth is 8/32" and the pattern is the same tread design found on the R6. They have been allowed in BMW Club racing and many other sports car clubs as well. Mounting instructions can be found in the “Road Racing FAQ” section of the website. The list of available sizes can be found in the "road racing/tire specs” section of our website.
When using rain tires, always increase your starting air pressure 2-4 psi over your dry tire pressures.
--------------------------------------------------------------------------------
Last edited by John Shiels : Today at 05:37 PM.
cars over 3,000 is me
http://www.hoosiertire.com/rrtire.htm
TIRE CARE TIPS
FOR R6 & A6 TIRES
(Download Printable Version)
The R6 and A6 have been developed to improve wear and consistency without any sacrifice of performance. In many cases, the performance will even improve over previous models. The new tire models are an evolution in the continuing effort to provide the best tire for racers.
- Tire Break-In Procedure
- Tire Temperature Recommendations
- Chassis Setup Recommendations
- Tire Pressure Recommendations
- Things to Consider
Tire Break-In Procedure
Proper break-in will not affect initial performance but will increase the competitive life of the tire.
The procedure can be broken down into phases.
1st phase: The initial run
2nd phase: The length of the time the tire is allowed to "cure"
The Initial Run Heat Cycle
R6 Roadrace
The first laps for the tire are critical for setting up the durability and competitive life. The first session should consist of no more than 10-15 minutes of running. The early part of the session should be run at an easy pace, with the speed gradually increased until the end of the session. The final lap should be run at the fastest possible speed. The intent is to achieve maximum tire temp on the last lap. At this point the car should be brought in and the tires allowed to cool at a normal rate.
During the initial run-in process, the inflation pressure should be 3-5 psi higher than you would normally use. The best progression would have the driver taking 4-7 laps to accomplish this break-in. Each lap should be approximately 7-10 seconds a lap faster than the previous lap. The goal is to have the tire temp as high as possible on the last lap without "shocking" the tire during the warm up laps. In essence, no wheelspin, late braking, or sliding. The last lap should be at, or very close, the maximum possible.
A6 Autocross
For autocrossing, the A6 does not need the same break in procedure as the R6. The A6 needs a minimal scuff-in session before the first autocross run. This “session” can comprise of simply driving around the event site at minimal speeds on the A6 set of tires. By scrubbing off the newness of the tread (no or minimal shininess remaining) prior to your first competitive run, the A6 tires will be more consistent in handling, grip and responsiveness on the first run. If this is not completed, running on un-scuffed A6 tires on your first run may result in the tires not gripping properly, or feeling like they “skate” over the course surface. You are welcome to run 3 – 5 psi higher when scuffing in a new set of A6’s, but be sure to reset them to the correct operating pressures before your first autocross run. As you compile autocross runs on your new A6’s, they should become more consistent in run times.
"Cure" Time
After completing the initial run phase, the length of time the tire is allowed to set is possibly more important. The barest minimum for this process to be beneficial is 24 hours. (Not "the next day"). Any less than this is a waste of time. The best situation would allow a week before using the tire again.
Proper tire management is a difficult process. To accomplish this almost always requires a second set of wheels. The payoff is greatly increased competitive tire life.
Following the recommended break-in procedure will require a lot of planning to make it work. The benefits to doing it right include greatly increased tire life as well as consistent performance and durability under stress. Please make an effort to educate your team on the importance of this. It can save you a lot of money.
Tire Temperature Recommendations
For best performance the expected temperature range will vary from track to track. Generally, optimum traction will be generated when the pit lane temps show 180-200 degrees for the R6 in Roadrace applications, and 140-150 degrees for the A6 in an Autocross application.
Note: Use of static infra-red pyrometers is an inaccurate method to monitor tire temps.
Chassis Setup Recommendations
For optimum performance the Hoosier P-Metric radial tires require about 3 degrees of camber. There will be a trade off in maximum performance to maximize wear. Generally, 1/2 degrees less than optimum will result in the best compromise for wear and speed. Less than 2.5 degrees can result in excessive wear on the shoulder junction.
The Hoosier tires typically offer better performance with spring/shock rates higher than previous brands you may have run.
Tire Pressure Recommendations For Competition
Traditionally, Hoosier tires have often required higher pressures than other brands. This has changed with the A6/R6.
Roadrace/track applications
Vehicle size
Recommended Hot Pressure
Cold Pressure
1800-2200 lbs.
34-37+
26-31
2200-2600 lbs.
35-38+
27-32
2600-3000 lbs.
37-41+
27-32
over 3000 lbs.
38-43+
27-33
+Higher pressures will improve the performance capability but will require a more sensitive feel to take advantage of the increase.
One characteristic of the tires is the tendency to "skate" initially (when inflation pressures are correct). It is important to resist lowering the pressure to attempt to eliminate this feeling. Dropping the pressure too far may improve the "feel" of the tire however it will also lower the performance and increase the wear rate.
Autocross applications
For autocross applications, your starting pressure for the first run should be within 1-2 psi of the recommended hot pressures shown above. After the first run and each subsequent run, keep resetting the pressures back to your target hot pressures before taking the next run. This way your tires are at the proper pressure during the bulk of every run you take.
The above chart is a general recommendation which is intended for a standard configuration vehicle (i.e. front engine, rear wheel drive). Factors which can radically affect your pressure set up would include front wheel drive, independent rear suspension, rear engine, McPherson vs. control arm front suspension.
Front Wheel Drive
Vehicles configured with FWD are probably the most difficult application for a tire setup. The combination of steering, braking and accelerating on the front tires, combined with higher corner weights for the front positions produce a harsh environment for the tire. These vehicles will typically have a strut type of suspension which limits camber gain. All these factors result in conditions which require the tire do more work than a simple chart for pressures can accommodate.
In severe cases front tire pressures for FWD vehicles can run in the 48-52 psi (hot). In cases where the tire size is limited to a relatively small tire, the required pressure can run even higher. The front to rear pressure differential on FWD cars can have extreme ranges of inflation, depending on the driver preference, suspension tuning, and track configuration.
Independent rear suspension
With IRS and proper geometry up front, tire pressures can be reduced from the recommendations listed above. When there is adequate camber gain and good roll control, the Hoosier radial tire will perform very well at the reduced air pressure. This results in a bigger "sweet spot" and easier control at the limit.
When tuning at reduced pressures use the following formula to determine the minimum safe pressure: Divide the total vehicle weight, including fuel and driver, by 100 to arrive at the minimum safe pressure. Example: Your car weighs 2750 lbs. as raced. The minimum safe (cold) pressure is 27.5 psi.
Extreme care should be taken when tuning at reduced pressure. Tire damage can occur that is not visible to external inspection.
Vehicles equipped with independent rear suspension (IRS) have a distinct advantage over non-IRS cars when using radial tires. This is true for two reasons. First, it is possible to setup some amount of static negative camber on IRS suspensions, if needed. Second, the IRS geometry can provide the proper camber gain to achieve the dynamic camber needed for a radial tire. This is a great benefit because it then becomes possible to better address front tire grip when the rear of the car can be optimized closer to the tire's potential.
THINGS TO CONSIDER
These tires are molded to their designed tread depth. They do not require shaving to be prepared for competition use.
Due to extremely light construction, Hoosier tires have a much lower polar moment than other radial tires. This translates to a very low rotational mass, which is a good thing for performance applications. The down side to this feature is that the tires do not resist "spikes" in braking force as well as a heavier tire might. As a result, there is a tendency for drivers to "flatspot" a tire the first time really getting to the limit. Vehicles equipped with ABS will benefit from its use. If you do not use ABS it is recommended that you make an effort to minimize stabbing the brakes until you have some experience with the feel of the tire under hard braking.
The light construction also provides less protection from impact damage and punctures. Off course excursions or running over debris on the track will likely result in tire damage.
The tires are not directional. Once some wear has occurred it may be desirable to flip the tire on the wheel in order to even out the wear and maximize tire life.
Wheel Widths
Wheel width dramatically affects wear and performance of the Hoosier P-Metric radial tires.
There is about a one inch window of optimum width. The trick is to figure out that window. A good rule of thumb to use for determining proper width is to use the tread width of the tire. Measure the tread width. Plus or minus 1/2 inch from the tread dimension will indicate the proper rim sizing. It is possible to use narrower wheels, but at a sacrifice to shoulder wear and cornering power.
"Measured" rim vs. "Recommended" rim
In our printed product catalog and on our website tire specifications you will see two columns of information regarding rim dimensions. In most cases, the "measured rim" and the "recommended rim" will be the same. However in the case of DOT tires, the information may appear contradictory.
The reason for the differences lies in the Department of Transportation requirements for publishing tire dimensions on any tire that carries a DOT certification. Each tire size has a specific rim that must be used when taking measurements for tire comparison. This is intended to allow consumers a consistent way to compare tire sizes between brands.
With respect to the Hoosier P-Metric line, the recommended rim size will typically be wider than the DOT standardized wheel.
The fact that a tire will "fit" on a rim is not an indication that it will work effectively in that condition. Radial tires are extremely sensitive to wheel widths. The performance characteristics of the tire can change significantly within the recommended range of application. Mounting a tire on a rim that is outside of the recommendation is not a good idea.
Driving Style/Braking
Driving style has also shown to significantly effect tire wear. Drivers who achieve their speed by "tossing" the car run the risk of increased tire wear. Radial tires develop their highest cornering power at relatively low slip angles. Smooth, tidy driving yields faster lap times and better tire wear.
The braking feel of the Hoosier R6 tire is very vague at the threshold. This is particularly true for "sticker" tires. Drivers need to develop a sensitivity for the limits under braking. This takes time and practice. Failure to apply this will result in flatspotted tires.
Particular care needs to be taken when selecting brake pad compounds. It is possible to have a pad that is too aggressive. This will make it very difficult to develop good braking fell for threshold braking.
Rain Tires
The Hoosier D.O.T. Radial tires are extremely good in dry conditions, however they do not make very good wet weather tires. Having dedicated rain tires available will be necessary for your team to be properly prepared. Hoosier makes a D.O.T. approved bias-ply tire called a "Dirt Stocker" that has been proven to be far superior to any competitors tire as long as it is a steady "wet" condition. Check with your Hoosier representative for size availability.
Hoosier Racing Tire also offers a D.O.T. Radial Wet tire. This tire has a molded tread of symmetrical design. Check the product catalog for the available sizes. The compound for these tires is intended for wet weather use only.
Hoosier also offers a non-D.O.T. radial rain tire based directly on the P-Metric R6 tire. The tread depth is 8/32" and the pattern is the same tread design found on the R6. They have been allowed in BMW Club racing and many other sports car clubs as well. Mounting instructions can be found in the “Road Racing FAQ” section of the website. The list of available sizes can be found in the "road racing/tire specs” section of our website.
When using rain tires, always increase your starting air pressure 2-4 psi over your dry tire pressures.
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Last edited by John Shiels : Today at 05:37 PM.
Last edited by John Shiels; 11-12-2007 at 05:58 PM.
11-12-2007, 05:56 PM
#10
Team Owner
I don't know about A6s on the track. I lightly corded the outside of one front at 39 laps AutoXing. Most of those laps were at a very grippy concrete venue, but still 39 AutoX laps is nothing. And I'm running -2.8 Camber so I don't think that was the issue. I should have had the tires flipped around 30-35 laps and I think I would ahve been lucky to get 70 total. I'm giving up on the A6 at over $1500/set 70 laps "if I'm lucky" just isn't going to cut it. I'd almost be scared to try a 25 minute HPDE session on A6s not knowing how quick they'd cord out.
-TJ
-TJ
11-12-2007, 08:38 PM
#11
Melting Slicks
John - The numbers you posted from Hoosiers website is exactly what their tech guys told me when I called. That was on the R6 and the Rolex tires. Roughly 40lbs/front and 38lbs/rear hot. They said don't drop pressures to get more grip unless you don't mind killing the outside edge or the shoulder. I had told them I had -2.0 camber front and -1.5 camber rear. They obviously told me they preferred -3.0 but the R6 was way more tolerant of less camber than the previous R5 and R4. I believe them. With only the addition of T1 bars I'm seeing even tire wear and temps across the surface. The only reason I'm flipping the tires is because the outside edge shows more rounding than the inside.
Frank - Are you just running a set for a race and then dumping them? Are you running massive camber? Any issues with outside edge or shoulder? I haven't dared to drop my pressures that much.
I haven't tried the V710 yet but very happy with the R6 running 315 front and 335 rear. The car feels flat out planted. I have 4 weekends on them and can probably do another 4 weekends. I got them with a couple of heat cycles on them. I honestly can't feel any drop off in their performance yet. They do not fall off hardly at all during a 30 minute session. The Rolex tires do and don't appreciate the way I drive. I doubt I'll buy them again even at the discount.
Btw, I ran those same R6s at an AX just for fun. It was a fast course. I helped design it
I started a couple of pounds below what I start with on track. They gripped surprisingly well after the 1st run.
Graham
Frank - Are you just running a set for a race and then dumping them? Are you running massive camber? Any issues with outside edge or shoulder? I haven't dared to drop my pressures that much.
I haven't tried the V710 yet but very happy with the R6 running 315 front and 335 rear. The car feels flat out planted. I have 4 weekends on them and can probably do another 4 weekends. I got them with a couple of heat cycles on them. I honestly can't feel any drop off in their performance yet. They do not fall off hardly at all during a 30 minute session. The Rolex tires do and don't appreciate the way I drive. I doubt I'll buy them again even at the discount.
Btw, I ran those same R6s at an AX just for fun. It was a fast course. I helped design it
I started a couple of pounds below what I start with on track. They gripped surprisingly well after the 1st run.Graham
11-12-2007, 09:05 PM
#12
Team Owner
I think when everyone was beating up on 03 or 04 Hoosier they were lacking enough camber. Those Hoosier were probably camber sensetive more tan the newer ones. Running the recomended 2.5 or 3 degrees camber on a street car would be tough on tire wear. I have 2.8 in the front and 1.5 i the rear.
Mine to are good for the whole session of 20-25 minutes. Victor races would get greasy so fast they would wear very quickly. So even though Hoosier cost me more I think it is at least even dollar per mile vs the Kuhmos I ran. I put 305 and 335 x 18's unfortunately I never made it to the track this year. I feel like I am in jail
Hoosiers are a bigger tire than most even in the same size as X brand.
11-12-2007, 09:51 PM
#13
Safety Car
I have run all of the tires, and my opinion, is that I like any new tire that I have best! Since I am poor, I usually run on old tires, so a new tire is a blessing.
That said, I am more of a Kumho v710 dude than a hoosier dude (never tried the r/a6--) Victorracers don't grip nearly as well as the v710.
Right now i've got a bunch of Falcon's hand me downs to run, so I don't see buying any new tires in my future, unless I get a set of wheels and tires for my 08 z06
That said, I am more of a Kumho v710 dude than a hoosier dude (never tried the r/a6--) Victorracers don't grip nearly as well as the v710.
Right now i've got a bunch of Falcon's hand me downs to run, so I don't see buying any new tires in my future, unless I get a set of wheels and tires for my 08 z06
11-13-2007, 12:25 AM
#15
Safety Car
I was shrugging the A6's off because of their short tire wear. But after reading this thread I think I'm heading towards them as opposed to the R6. I am fairly fast, but for some reason, I dont eat through tires very fast. I got 24 cycles out of R3's, and will likely get more than 10-15 out of some Yoko scrubs I bought.
So A6's will be my 08 Time Trials Tire of Choice then.
How do they act after their prime though. I know the peak may be higher, but is the remainder of the time on them far off the R6?
So A6's will be my 08 Time Trials Tire of Choice then.
How do they act after their prime though. I know the peak may be higher, but is the remainder of the time on them far off the R6?
11-13-2007, 12:36 AM
#16
Drifting
Based on this thread, I may experiment with higher pressure. I'm ending at 35-36 hot, and it seems Hoosier prefers higher. Interesting. I was thinking I was around right. I am getting outside edge wear on the R6s I have on the car now, esp. the front. Temps across the tire look about right, in terms of gradient, but seem a bit low. Will try higher next time out.
I've run A6 and R6. The As are faster. Around 1-2 seconds on a 3 mile track, for me. Perhaps more, as I didn't test both in the same weekend, or with the same suspension setup. YMMV.
I've run A6 and R6. The As are faster. Around 1-2 seconds on a 3 mile track, for me. Perhaps more, as I didn't test both in the same weekend, or with the same suspension setup. YMMV.
11-13-2007, 07:03 AM
#17
Tech Contributor
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This question may seem a bit out of place, so I apologize if it is. Has anyone tried the Kumho Ecsta V700s? NOT the 710s, but the ones with some tread on them? I know they won't be as sticky as the Hoosiers or even the V710s, but, how do they hold up at the track (considering they do have tread on them?) How do they compare to the old Kumho Victoracers? Any input?
I ask because I drive to and from the track with my R compounds on the car. I won't dare do that with Hoosiers or V710s, so I'm not even about to consider them (the Hoosiers are also rediculously priced IMHO).
Thanks.
jas
I ask because I drive to and from the track with my R compounds on the car. I won't dare do that with Hoosiers or V710s, so I'm not even about to consider them (the Hoosiers are also rediculously priced IMHO).
Thanks.
jas
11-13-2007, 08:17 AM
#18
Drifting
This question may seem a bit out of place, so I apologize if it is. Has anyone tried the Kumho Ecsta V700s? NOT the 710s, but the ones with some tread on them? I know they won't be as sticky as the Hoosiers or even the V710s, but, how do they hold up at the track (considering they do have tread on them?) How do they compare to the old Kumho Victoracers? Any input?
I ask because I drive to and from the track with my R compounds on the car. I won't dare do that with Hoosiers or V710s, so I'm not even about to consider them (the Hoosiers are also rediculously priced IMHO).
Thanks.
jas
I ask because I drive to and from the track with my R compounds on the car. I won't dare do that with Hoosiers or V710s, so I'm not even about to consider them (the Hoosiers are also rediculously priced IMHO).
Thanks.
jas
11-13-2007, 01:08 PM
#20
Tech Contributor
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