: 2011 CTS-V Coupe Standard equipment tires.

06-02-12, 09:46 AM
Hello. Does anyone know what the reason is for the taller diameter tire on the front of the car. It is a 40 series versus 35 for the back. Except for the width of the tire, I would think the taller tire should be on the rear.

06-02-12, 09:55 AM
1) wrong subforum.
2) the 35/40 portion of the tire size correlates with the width. Measure the diameter and I am sure they are closer than you think.

06-02-12, 06:18 PM
(1) I agree, wrong subforum.
(2) I agree, the 2nd number in the tire size is not the sidewall height, it is the sidewall ratio. I don't have a 2011 V coupe, but I'll bet you the sticker price that the rear tires are wider than the fronts. Thus, a smaller ratio is need to maintain the same diameter. There are a million sites that explain tire sizing - visit Tire Rack's tech section, for instance.

06-02-12, 07:16 PM

06-03-12, 09:17 AM
The 35/40 is the aspect ratio. That means you take the first number(the tread width) and multiply that by the aspect ratio to get the sidewall height.


255 x .40 = 102
285 x .35 = 99.75

So its almost equal. Some, when replacing tires have gone to a...

295 x .35 = 103.25