I cannot get the speedo right on my ppe. I have 285/70/17 wheels... I feel like I have tried every 1/4 inch and can't get it right.

Anybody know what the exact size tire to input to get the speedo right is?

My tire size is 285/65 R 18 they measure 31.25 in height. To get my PPE accurate I had to set it at 32.25 it is dead on now.

I had the same problem with my 265s. Went to tirerack.com and looked up the specs for my tire and got the correct tire height, worked fine with that.