I have a ppe xcelerator, and aftermarket exhaust but don`t want to install them until i get more miles on my truck to keep the warranty as long as possible. I`ve put 285/70/17`s on the truck and am wondering if i can use my tuner only to input the tire size to keep the speedometer correct? my concern is that it will void my warranty if i plug it in. any ideas?

To correct the speedometer requires rewriting the ECM tune. So if you use the tuner just to correct it then you have done the same as if you had tuned it for more power and or DPF delete and so forth. No way around that. Only possible choice is using an Edge module system like the juice with attitude and setting the tire size on it but it will not correct the speedometer. You would have to look at the Edge display to see the speed that it calculates. Also the Edge Insight will do the same to see what you would actually be going.

Brian

is it possible for the dealership to correct this?

It is my understanding that the GM Tech II does not offer that size for the trucks. Only 245 and 265 options. But it has always been some saying yes and some no. I would really like to see a screen shot of a GM Tech II tire size.

Brian