Yes, stupid question, but I've never gone with anything other than stock sizes and I need to be sure.

Running Eagle F1 GS-D3's all around, I need new rears, but the size is out of stock everywhere, even the Goodyear shop couldn't find any.

I have stock 17's....stock size is 235/50. I need the closest thing to it that won't trip up TCS and won't be too wide.

Tire calc results:

235/50 (stock): 82.46 circumference

245/45: 80.67 circumference 2.18% difference
255/45: 81.77 circumference 0.84% difference

Annnd those are the only two in stock somewhat close. Would 255/45 be cool, or what?!

 

I wouldn't recommend running a 255 on an 8" wheel, but its probably okay.

 

Yeah, that's my only worry...but is 245/45 (2.18% difference) cutting it too close for VDC/TCS?

 

Do you drive a automatic Touring with 17 inch wheels?

 

Yes. 8" width in rear. Fronts 225/50-17 // 7.5" width.

Also considering running the OE front size in the rear....Can't find the 235/50's anywhere...

 

I ran 245/45 F and 255/45 R for a year's worth of autocross and DD. They work great.

As long as the tire co says a given size is ok for a given wheel width, I wouldn't wory about it.

Goodyear says 8-9.5" wheel width is ok for the 255/45 17 tire.

http://www.tirerack.com/tires/Spec.j...irePageLocQty=

I would go with that.

And when the fronts need to be replaced, I would go with the 245/45 17's there.

 

Then you have TCS not VDC. There is little need to be concerned about satisfying VDC with perfect differences in overall tire heights.

 

what about stock 18s i need some new rears too

 

Why don't you just find a set of OEM's that are newer on this site ?

There are some great deal out there....for instance......

https://my350z.com/forum/showthread....314909:icon17:

 

Your rears on stock 18" wheels is: 245/45-18"

--Spike

 

but can i go 255's? can't i ?

 

Weird

 

I'm not gonna mess with sizes since I'm only changing the rears....going to go with the new similar Eagle F1 Allseason performance tires in the right size.

 

Autocross racers with TCS can run the same size tires all around with no problem. But there is no 100% guaranty that mismatched tires with TCS will work.

I went from Eagle F1 GS-D3 to Eagle F1 Allseason performance. I am sure that you are smart enough to be cautious with oversteer. Try the new set-up in an empty parking lot before you push the car.