Originally Posted by Armitage

Is a 35 series sidewall still enough rubber to protect the rim?

I'm looking into this same exact situation right now (Work Emotion CAI) but I am looking at running the +20 application, 8.5" up front and 9.5" rear. I was going to run 245/40 in the front and 275/40 in the rear as this seemed to be the optimal setup, but the KDW-2's don't come in a 275/40 but they do come in a 285/40. I am not lowered yet.

From what I've researched:

225/40 --> 255/40 = .2% too slow on the speedo
225/40 --> 255/35 = 3.6% too fast on the speedo

245/40 --> 275/40 = .01% too fast on the speedo
245/40 --> 285/40 = 1.1% too slow on the speedo
245/40 --> 285/35 = 3.1% too fast on the speedo

I don't want to upset the VDC either if it detects a difference between the tire speeds if I run a 40 series up front and a 35 series in the rear.

Originally Posted by redlude97

285's are the widest recommended width for a 9.5, so 285/40/18 if you can find it