Tire Upgrade Questions

[CUTiger22]

Hey everybody, im new to the forum, Chevy trucks and full size trucks, so bare with me. I recently bought an 08' Silverado that came with 245/70/17 on it. I want to upgrade to either 265/70 or 285/70. How much would my mpg change and would i need to get my speedometer calibrated ?

[LURCH HD]

You could the 265's without a leveling kit the 285's will need one.

Yes you will need a tuner to reset your speed-o.

The gas mileage loss will depend on different thing's, size of engine, rear gear ratio and such but if I had to guess I'd say 2 to 4 mpg

[CUTiger22]

You could the 265's without a leveling kit the 285's will need one.

Yes you will need a tuner to reset your speed-o.

The gas mileage loss will depend on different thing's, size of engine, rear gear ratio and such but if I had to guess I'd say 2 to 4 mpg

 

Thanks for the help.