C4 race slicks...Go same size F/R or split like stock?
05-03-2007, 10:41 AM
#1
Race Director
Thread Starter
C4 race slicks...Go same size F/R or split like stock?
Im thinking about getting some Kumho 710's .
I have a 1993, so I have P255/45R17's on 17 by 8.5 fronts and
P285/40R17 on 17 by 9.5 rears.
Should I go P275/40R17 Kumho 710's all the way around so I can rotate, etc. easier.
Or should I go split them up like stock?
Kumho 710's do not come in P285/40R17, but come in P245/45R17 and P275/40R17's which is close enough for me.
I have a 1993, so I have P255/45R17's on 17 by 8.5 fronts and
P285/40R17 on 17 by 9.5 rears.
Should I go P275/40R17 Kumho 710's all the way around so I can rotate, etc. easier.
Or should I go split them up like stock?
Kumho 710's do not come in P285/40R17, but come in P245/45R17 and P275/40R17's which is close enough for me.
05-03-2007, 10:49 AM
#2
Melting Slicks
C4's, being camber challenged on the front tend to understeer and need as much rubber as you can get on the fronts.
The best choice would be to upgrade to the Z07 springs and sway bars. Then you could legally go to 9.5 inch wheels all around and you would have a much better autocross setup. That's pretty much what the car needs. I am assuming SCCA rules here, and in order to be legal you need to put on the springs and bars (it was a complete suspension package, springs, bars, and wheels) in order to get the 9.5 inch wheels and then you can use 275's all around.
If you are getting serious enough to put 710's on the car it is time to upgrade to the springs and bars. It doesn't cost all that much, you can do it in a day, and the car will be much better overall.
You can pick up two sawblade wheels pretty cheap and do it all.
The best choice would be to upgrade to the Z07 springs and sway bars. Then you could legally go to 9.5 inch wheels all around and you would have a much better autocross setup. That's pretty much what the car needs. I am assuming SCCA rules here, and in order to be legal you need to put on the springs and bars (it was a complete suspension package, springs, bars, and wheels) in order to get the 9.5 inch wheels and then you can use 275's all around.
If you are getting serious enough to put 710's on the car it is time to upgrade to the springs and bars. It doesn't cost all that much, you can do it in a day, and the car will be much better overall.
You can pick up two sawblade wheels pretty cheap and do it all.
05-03-2007, 10:49 AM
#3
Safety Car
You have two options to be cost effective:
Go 275 all the way around
Go 275 front and 315 rear.
These are the most common sizes, meaning you can get new tires a little cheaper (and more available), and scrubs are abundant.
i recommend to start that you run 275's on all 4. Get some scrubs and try them out. If you need more grip then go up to 315's, but I assume you'd need some bigger wheels for those. The 275's fit nicely on the stock 9.5" front rims.
Go 275 all the way around
Go 275 front and 315 rear.
These are the most common sizes, meaning you can get new tires a little cheaper (and more available), and scrubs are abundant.
i recommend to start that you run 275's on all 4. Get some scrubs and try them out. If you need more grip then go up to 315's, but I assume you'd need some bigger wheels for those. The 275's fit nicely on the stock 9.5" front rims.
05-03-2007, 10:55 AM
#4
Melting Slicks
V710's also come in 295/40-17's. I am presently using the 275 front, 295 rear on 9.5's and I like it a lot. It is also the fastest setup I have ever used in laptimes(but there are so many other variables.) My hot pressures are 37 front and 34 rear.
However, I have also used the 275 all around setup and it is the economical because of tire longevity. With this stup, I rotate front to rear after an event, then dismount and swap to the diagonal wheel. I squeeze 4 events out of $75 scrubs! I also use Traction V compound to freshen the tires prior to each event.
However, I have also used the 275 all around setup and it is the economical because of tire longevity. With this stup, I rotate front to rear after an event, then dismount and swap to the diagonal wheel. I squeeze 4 events out of $75 scrubs! I also use Traction V compound to freshen the tires prior to each event.
05-03-2007, 11:11 AM
#5
Race Director
The traction compound help? I have been running 285 MX all around, they work well and it helps a lot to rotate. No trouble driving to tracks.
05-03-2007, 02:20 PM
#6
Race Director
Thread Starter
How many events can I get out of these things? (Kumho 710's)
I realize they say one, but come on!
Im planning on using these for Auto-X, Road Race, and drag race (rears only).
I do about 7-8 one day events a year.
As for the tread hardening, I will shrink wrap the entire tire/wheel if I have to to preserve the cmpd.
I realize they say one, but come on!
Im planning on using these for Auto-X, Road Race, and drag race (rears only).
I do about 7-8 one day events a year.
As for the tread hardening, I will shrink wrap the entire tire/wheel if I have to to preserve the cmpd.
05-03-2007, 04:50 PM
#7
Melting Slicks
You can figure about 60 autocross runs on a set before they start to harden up. That was with two drivers and cooling down between runs.
There was plenty of tread left, but the grip went away big time.
We did find that they lasted longer if you cooled them more between runs, the hardening factor was more like a time at temperature thing. The older they get the hotter you need to get them for them to work.
Formula V helped, but not as much as on some other tires I have used it on.
Not sure how many HPDE's sessions you can do on a set.
I didn't find them to be very sticky on launch at typical autocross pressures. I didn't use them on the strip where the track is treated, they might be better on that kind of surface. Maybe they would be better if you let them down to lower pressures at the strip, but drag radials are likely a lot better for launch.
There was plenty of tread left, but the grip went away big time.
We did find that they lasted longer if you cooled them more between runs, the hardening factor was more like a time at temperature thing. The older they get the hotter you need to get them for them to work.
Formula V helped, but not as much as on some other tires I have used it on.
Not sure how many HPDE's sessions you can do on a set.
I didn't find them to be very sticky on launch at typical autocross pressures. I didn't use them on the strip where the track is treated, they might be better on that kind of surface. Maybe they would be better if you let them down to lower pressures at the strip, but drag radials are likely a lot better for launch.
05-04-2007, 07:21 AM
#8
Burning Brakes
Another vote for running the same size on all four corners, 275 or 295 if you can get them. I have a 93 as well and used to run the 275 V710 setup all the way around and liked it a lot.
One thing I found: make sure you have enough toe in on the rear or you'll tend to get snap oversteer.
One thing I found: make sure you have enough toe in on the rear or you'll tend to get snap oversteer.
05-04-2007, 12:43 PM
#9
Burning Brakes
Member Since: Jan 2005
Location: Littleton CO
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St. Jude Donor '07
I run the same size on all 4 corners. Have -2 camber in front and rear. The C4 really needs it to keep all the tire contact patch on the ground.
315's on all 4 myself on 17 X 11 rims... for both auto-x and track.
315's on all 4 myself on 17 X 11 rims... for both auto-x and track.
