View Single Post
      10-30-2012, 12:01 PM   #6
dchao
Private
2
Rep
69
Posts

Drives: BMW X2 M35i
Join Date: Oct 2012
Location: London

iTrader: (0)

Quote:
Originally Posted by edx1 View Post
That makes sense for the most part, but since the front is a /45, why didn't they do 255/45/R18 on the rear instead of 255/40/R18?
As jctg has explained:

(more or less - 0.45x225 = 101.25, 0.4x255 = 102, so overall difference in diameter is just 0.75 x 2 = 1.5mm).

101.25mm and 102mm are the height of the sidewall for the front and rear tires. The difference is negligible due to difference in tread wear and tire pressure.

Now that the rims are the same at 18" front and rear. Plus the same height of the rubber. The result is that, the chassis will sit level to the ground, instead of tilting forward.

Understeering has more to do with the fact it is a front-engine car. If you have a rear-engine 911, then it will be more prone to over steering. Like I said, if you have the Performance Control, then the xDrive will add a little bit of over-steering to correct the inherited under-steering the car has.

The only cons with staggered wheels is that you can't rotate your tires to get better milage out of them. So in the long run it will cost you more. On the other hand, it will definitely improve the handling and stability of your car, thinner front tires also makes steering lighter, useful for the hydraulic steering we have on xDrive.

Last edited by dchao; 10-30-2012 at 12:24 PM..
Appreciate 0