I just got 20s placed on my Z.. The sizes are 245-35-20 FR and 275-30-20 Rear and I notice it slips in the rear when going on a curvey road at 30-40 miles. THE LIGHT comes on SLIP. Does anybody know why this might be? Any Suggestions?

 

your car is not actually slipping. The reason why its saying your slipping is because you have a 35 tire in the front and 30 in the rear.

 

Can you please explain. Should i just turn off TSC?

 

Your cars computer is designed to have a taller rear tire than the front. Since your front tire is equal or taller than the rear you car thinks they you a breaking traction all the time.
Just turn off TCS or buy a 245/30-20 front tire.

 

Thanks,

What are the downfalls of having TCS off?

 

Do you know what TCS means? I feel like you need to search

 

You don't have traction control when its off LOL

 

Are you sure about that because he has the right tire sizes the 35 in front is to compensate for the 275 out back aspect ratio

 

Stock tire size 225/45-18 and 245/45-18 the rear tires are 3/4 inch TALLER than the fronts. When you upsize, you still need to need to keep the stagger in tire height between front and back.

 

Welcome newbie. Did you read the Top 100 Questions thread? This very subject is discussed there. Read it and you'll find your answer.

 

Issue is Fixed.. solution

changed ufront tires to 255/30/20... So Happy Now! Thank you!

 

So you figured out that the Front and Rear profiles should be the same (30/30 vs 35/30).

 

Not true that both the front and rear tires have to be the same sidewall profile. The stock 07-08 Z33 Nismo tires are 245.40F and 265.35R.

Correct me if I'm wrong but as long as the rears are within a 3% variance taller than the fronts, TCS should not kick in (although it's probably not a good idea to go 40F 30R).

 

They don't HAVE to be the same in general, but for the standard upgrade sizes of 245/275, they do need to be the same. You can pick other width and profile combinations as long as you keep the proper stagger. In OPs case, with 245/275 and 35/30 profiles, the fronts were taller than the rears, that's a definite no-no with TCS/VDC. All was explained in the Top 100 Questions thread.

BTW - run the numbers on those sizes and you'll see that the front is 25.7" OD, the rear 26.3", well within the accepted 0.25 to 0.75" stagger required.

 

That is true, but they also run an 18 in the front and 19 in the rear. That combo gives you the proper stagger in tire height.