vettenoir

I'm currently running 255/45R17's on 8" rims all around. Would putting 275's on the rear on 9.5" or 10" rims on the rear make a noticeable difference traction-wise for auto-crossing or HDPE, everything else being equal? Check out my signature at the bottom for the car's specs.

Thanks,

Bob

rfn026

Changing the tire size does not increase the size of the contact patch. The size of the contact patch is determined by the weight of your car and the air presssure of the tire. Changine tire size will change the shape of the contact patch but not the size.

Richard Newton
Corvette Race Car Blog

bobmoore2

Richard's (rfn026) reply is completely correct, but it doesn't really address your question. Putting wider tires on your car will result in a better shaped contact patch, especially with side loads, which will result in better grip in curves.

The answer is "Yes".

vettenoir

It took some noodling on the 'contact patch depends on weight & tire pressure' concept, but I get it.

Thanks for the advice

Aardwolf

Keep in mind that if they weigh a bunch more it will soak some HP which could result in no gain for lap times. So keep an eye on the weight! The stickiness of the compound plays a large role, perhaps just use stickier tires?

vettenoir

Thanks, I never thought of weight, but I'm looking to add ~100hp to the power plant, so hopefully that will cover any weight increase . I'm running Kumho MX's right now, any suggestions for a stickier street tire? I drive my car to/from events (50-200 miles each way) and don't want to have to change tires for competition. The MX's were a huge improvement over the Ecsta 712's that they replaced.

Bob