Wheel/Tire help

[Jtanner129]

Hey guys, new to the forum. I just bought a Sierra Crew SLE. The price was right and I never really noticed how much I hate the stock wheels and tires. The tire size is 255/70R17. I will be adding a RC 2" leveling kit and was hoping to put 20" helo 835 wheels with 275/60/R20 Cooper Zeon LTZ on it. My concern is that my speedo and MPGs will be way off. How easy can the truck be recalibated for the new tire height? Also will I have any braking issues with the larger tire? And is there anything else I should worried about?. Thanks for your help, you guys seem to really know what you're talking about based on other posts I've read.

[Danthaman69]

If your just going to a 275/60/20 dealer can change that for free. No issues with brakes either. Not a big enough tire to worry about. No issues should come up. 2" leveling kit is very common and really easy to do.

[Chris]

Speedo will be off some. And the dealer can not recalibrate for larger than stock tires from my experience

[Jtanner129]

Thanks guys,

[Jtanner129]

I spoke with a local gmc dealer, he said that they could re calibrate the truck to the largest standard gm tire size which is a 275/55/20. at least that will get the speedo and mpg calculator closer than leaving it set on the current size.