That's the rolling diameter of my front vs. rear tires. Stock is 26" and 26.7". I keep reading something about the difference between front and rear should be >.5" and <.7" or the ABS/VDC may not function properly.

Is this 100% accurate and documented somewhere? If so, I'll have some brand new 255/45/18 S-03s for sale soon.

 

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from what i know (i called tirerack on this) you should always keep the overall diameter of the wheel/tire comb. for 18" wheels the only tire sizes that work is the stock sizes, and 245-40 (front), and 275-40 (rear)..to go with 18x8.5 and 18x9.5.

 

Call America Tire to make sure. That's where I saw the documentation of the tire size difference requirement. I didn't see it in the owners manual. But who knows, it might be written in the service manual.

 

This is correct. The stock config of the Z has the rear tires about .7 inches bigger in circumference (diamater?). Anyways, like on my 18 stockers it's 245x45x18 in back and 225x45x18 in front. So the rear are a bit bigger in circumference.

 

Rule of thumb given to us by Nissan USA is:

No less than 1/2" No more than 3/4"
to keep everything computer controlled happy.

 

Well how does that figure in with the 17's I calculated the OD of the front at 25.86 and the back at 26.25 or only 0.39 difference???

 

You mean no less than 1/2 inch difference from stock to aftermarket, no more than 3/4" over right? Stock front to back the rear tires are 3/4" taller.