different wheel sizes

[deanprichard]

suppose i want to run 16" wheels up front (more brake clearance) and 15" wheels in the rear (wider tire selection). what effects will this have on handling if the tire diameters stay about equal? what effects would it have if i had even bigger tires (sidewalls) in the rear? im still learning about suspension and handling, but i know cars such as c5's, c6's ,prowlers, etc use dramatically different size wheels, but in the opposite pattern with bigger wheels on the rear.

did a search really couldnt find anything directly relevant

[IROC]

I don't know how directly relevant it is, but I run 8x16s in the front and 9x17s in the rear. Works fine for me. Are you talking handling effects on the street or at the limit on the track? For street use, I would say it's a non issue. For track use, selction of tire sizes, etc., would play into it, but ultimately it's not a no-no.

[deanprichard]

mostly street. some auto-x , de

[Bill Verburg]

Originally posted by deanprichard
suppose i want to run 16" wheels up front (more brake clearance) and 15" wheels in the rear (wider tire selection). what effects will this have on handling if the tire diameters stay about equal? what effects would it have if i had even bigger tires (sidewalls) in the rear? im still learning about suspension and handling, but i know cars such as c5's, c6's ,prowlers, etc use dramatically different size wheels, but in the opposite pattern with bigger wheels on the rear.

did a search really couldnt find anything directly relevant

You are opening a can of worms. Several things will happen some are corectable thru chassis tuning some are not or at least wil be hard to overcome.

First(worst) you will have less grip and higher slip angles on the back. i.e. more oversteer

Second(probably correctable) the rake of the car will be out of whack, aero balance will be affected, it does depend on the tire though chose a tall enough tire and this is ok but the previou issue will be worse, not to mention the potential gearing effects

I disagree that there is a better choice of tires in 15.

There are very few brake choices that fit in 16 but not 15.

[deanprichard]

thanks for the reply bill

ok oversteer, correctable through sway bar tuning. this is due to a higher slip angle in the rear?

rake of the car is not an issue really either as im building the car from parts and that will all be adjusted in the end with coilovers on both ends.

gearing, thats not really that big of an issue either i have a 7:31 ring and i will try to keep the diameter of the rear tire as low or close to stock as possible.

this is all just theory as i am not sure if my brakes will fit in a 15" wheel, but the smaller sidewall in the front will be a better choice than the 15's in the front, correct?

problem is im looking for 315's or maybe a little wider in the rear and there isnt much for 15's and i cant find anything for 16's. looking for a mostly street tire here.

15's and 16's are my choices since i cannot find anyone to make steel custom wheels in 17's or bigger. and i want to get some cheap wheels to start on.