ok so 2 questions...

a) since the front tires have nothing to do with the drivetrain, does it matter if the overall diameter chances??

b) what are the consequences of running a bigger diameter tire in rear? smaller? (the diff is +/- 1" off the diameter of the oem tires)

tia
vick

 

The consequences, as I understand them, are that the VDC doesn't like changes in diameter over a certain amount, what that percentage is I don't know. Many have run smaller or larger than OEM with no problem. 1" larger diameter should pose little problem.

 

The obvious thing is the speedometer will no longer be accurate it may be close though. Smaller tires will cause you to rack up more miles on your car and hurt your fuel milage slightly as the tires will do more revolutions per mile than OEM sizes. The larger will have the opposite effect. Stick as close to oem size as you can small changes will only have very minor effects that will not be that noticable. If you look around you can find a wheel size calculator that will tell you how much your speedo is out.

 

5% or less difference in overall circumference of the wheel/tire compared to rear, or the VDC will have a fit. Have to keep changes within that boundary or it will pick up on the differences in wheel speed as "wrong".

One inch overall increase front only will almost certainly cause issues on cars with VDC. A fair amount of Z's did not have VDC, just TCS, that's why you see more same-size all around sets on Z's.

Check my350z top 100 questions, details on sizes there apply to G35 Coupes for right-sizing, too.

 

Read my two posts here:

https://g35driver.com/forums/wheels-tires/230051-tire-wheel-upgrade-affect-mileage.html