DJmaya

Hi guys,

I know this subject has probably been answered a few times in the forums but i cannot find a post that has all the information clear.

My C3 has all kinds of mechanical upgrades but it looks completely stock. This includes the wheels and tires. I recently moved to Seattle and I am now driving my car on a very frequent basis. It has now become obvious that my tires are horribly outdated and cannot perform under the power that my car has.

I looked for better tires for my stock 15inch rims but all I find are truck tires. So I have decided to go to 17s or 18s which have all kinds of options for high performance all weather tires. This also gives me the opportunity get wider tires however I do NOT want to have different size for front and back.

I have the bolt pattern and the rim+sidewall size figured out to maintain the same overall wheel diameter and not mess with my speedometer.

Now my question is, how wide can I go with my wheel? I do not want to have any mods or have to move my e-brake but I definitely want to avoid rubbing.

I am looking for answers that tell me the tire width and the wheel width and backspace I need.

Thanks ahead guys.

Brass Pass

I have American Racing 17x8 Torq Thrust II wheels with 255/45ZR17 tires. I'm pretty sure you can go a bit larger in both the 17" and 18" wheels, but I went with the safe bet.

bluedawg

I'm in the same boat. At the top of the page in the sticky section their tire and wheel upgrade thread that has pages upon pages of combos.

Illegal Vette

After reading and re-reading the wheel upgrade thread, it looks to me like 8" wide on the front with stock backspace and a 255/45 18 tire (if your car originally came with that width tire), and 10" wide on the rear with 5 or probably 5.25 inch backspace and a 285/40 18 tire.

chevymans 77

[QUOTE=Illegal Vette;1587433303]After reading and re-reading the wheel upgrade thread, it looks to me like 8" wide on the front with stock backspace and a 255/45 18 tire (if your car originally came with that width tire), and 10" wide on the rear with 5 or probably 5.25 inch backspace and a 285/40 18 tire.[/QUOT]

To fit a 10" wide tire on the rear you will need to move the E-Brake bracket, if you want the tires to be under the fender.

Neal

jb78L-82

I have SLP 17 X 8 rims-hyperblack-255/45/17-fit perfectly. In terms of performance, not looks, you really do not have to go wider or lower profile. Very important!!!!-Whatever you chose for a tire, make sure that the tires are ultra high performance summer only V (better)/Z (best) tires. Stay away from S/H/T rated tires. Traction AA/Temperature A.

DJmaya

Doesn't that give you a smaller overall diameter than the stock wheel/tire combo?

DJmaya

Thanks for the advice. I am looking at Ultra high performance all season thinking summer tires would not perform well under rain.

The reason I am changing the my tires is that I moved to Seattle and I drive my car year round. I actually commute to work in it.
Concerns:
Wet roads are really scary with so much power (335HP/375torque) and such crappy tires.
Breaking locks my tires quite easily.
I have a very loose center feel with the stock bubble tires at speed 75mph+
I want to maintain the wheel diameter because i already have very low clearance 3.25 inches because of the headers in my car and it is very hilly here so every once in a while i get to an intersection at the top of a hill where ever little clearance counts.

Brass Pass

I don't know. What is the difference you reference?

My tire and wheel combo meet three main criteria... They perform, look good and fit with no issues.

Good luck!

jb78L-82

Actually, Summer only ultra high performance tires have BETTER traction in the rain than all season high performance tires. All season tires are a compromise of dry, wet, cold, light snow traction which means that they can't compete with a summer only tire that has to have great dry traction and wet traction at high speeds, no less-they also wear faster with stickier rubber which is a benefit in the dry AND the wet. My Chrysler 300 has 245/55/18 ZR all seasons as well as my 2001 Grand prix (225/55/16 ZR all seasons)-I am careful in the rain with both. My other cars with summer only high performance Z's are much more surefooted in the rain. Hope that helps!

255/50/17 tires are exactly the same diameter as the 255/60/15 OEM tires. My 255/45/17's are about 1 inch shorter than the 255/60/15 OEM tire.

DJmaya

The stock tires for my 77 are 225/70R15 27.4 inches in diameter
your 255/45/17 are 26 inches.

Ifi was to put those tires my speed would be 85.4mph when my speedometer would be say 90pmh

jb78L-82

This is true that the speedo will indicate higher than the actual speed but the bigger issue is that you will need more revs to achieve the same speed with the smaller tire. My 01 Grand prix has slightly smaller tires- diameter/lower profile tire than the OEM tire and at 80 MPH with the OEM tires 80 MPH is 2,300 RPM and 2,500 RPM with the smaller/lower profile tire. Using smaller tires makes the car feel
like you have a higher numerical gear in the rear end.

gkull

you can use 255/50/17 fronts with 4 inch BS. my front wheels are 17X9

I originally tried 285/40/17 I'm not sure why anybody would want all four tires the same size. I wish that the ultra high performance tires had less width on the rain grooves, but even in pouring down rain I hardly have to slow down

I have some pictures on the old CF home page

http://www.corvetteforum.net/c3/gkull/

Illegal Vette

[QUOTE=chevymans 77;1587433998]I had my car up in the air yesterday, and I can see that you're right. The e-brake bracket is very close the the stock wheel. If you cut off the bracket and relocate the cable that frees up 1 1/2 inches at the trailing arm. So with a 10 inch wheel and 5 inch backspacing it would be an inch wider on the inside and the outside. I don't know how close this puts the inside of the tire to the wheelhouse.