I'm running Nismo wheels with the usual 245/40/18 front and 275/40/18 rear set-up. My question is why did Nissan recommend this differing rolling diameter set-up? A 275/35/18 tire would give the same rolling diameter as the front 245/40/18. I have a roadster without VDC. Would there be any downside to using a 275/35/18 tire in the rear? Does the odometer reading come off rear or front wheel rotation?

 

quote "My question is why did Nissan recommend this differing rolling diameter set-up"

i presume its because nissan wouldn't recommend something that doesn't work with all their 350z models - for example, it will change the speedo. they pretty much HAVE to recommend that size.

and it's not just VDC that would be a problem. do you have TCS or want your speedo to be accurate?


pp

 

smaller sidewall in back...most tire vendors don't recommend it, like tire rack, discount tires, etc.

 

the reason why nissan recomends 245/40/18 / 275/40/18 is:

They share the same tire DIAMETER STAGGER front and rear as the stock tires...

For every 1 rotation of the front tires, the rear tire must rotate 1+A more.

If you do the 275/35/18 you will have a slightly shorter tire in the rear... making for evey 1 rotation of the front tire the rear tire will rotat 1-A.

This will throw off the VDC system...

If you do not have VDC, you can run the shorter tire size, your speedo wont be accurate though...

 

^like he said, it approximates stock stagger from front to back, but 255/275 is even closer to stock than 245/275.

 

255/275 set-up works great

 

That's not correct.

For every 1 rotation of the front tyre, the rear tyre does 1-A rotation. That's because the rear tyre diameter / circumfrence is larger than the front tyre's diameter / circumference.

 

so I wrote it wrong...

Its saturday night... Jason is aloud to have fun too

For every rotation of the front tire the rear rotates a little LESS

21 revolutions per mile difference... with the stock 225/245 tire size

If the VDC senses that the rear tires are going to rotate any faster compared to the fronts then the VDC kicks in...

vice versa for the front if they slide or something...

as long as the ratio between front and rear rotation is within tollerance of my guess is 10 revolutions per mile, the VDC system is not effected..

but once they are about the same it is...

there is a way around this that is very simple to re-calibrate the VDC for other tire sizes...

turn the car to on position: roll backwards 15-20 feet / roll forwards 15-20 feet

its suposed to work atleast...

 

All's cool.

 

I get the point of trying to maintain the same overall rolling diameter as stock in the rear. I guess my real question is why did Nissan set up the rear with a larger rolling diameter than the front? What is the advantage in doing this?