I've got a 2007 LT Tahoe w/ stock 17" wheels. I've just purchased the 20" stock LTZ wheels. I've heard that the speedometer will be off after I install the 20's and need to take it to the dealer and have them reset the computer so that it recognizes the 20's. Does anyone know if this is true? Are there any other impacts or changes that I need to be aware of by adding the 20's? Thanks in advance!

 

Rim diameter is irrelevant; it’s the tire’s diameter that is important (for MPH). Check tirerack.com and check your 2 tire sizes, if the diameter of the outside of the tire is the same, or close enough, I wouldn’t bother… but since the 20” rim + tire is a factory combination, they should be able to adjust it if needed. Most of the time when you up rim size, you are reducing sidewall size… so you have same 'size' tire on the outside, just not the inside... unless you got some 35" tires for it, I doubt its way off... I think the Tahoe is around a 31" factory (don't quote me).. if I wear out my tires on my 95 I want to see if I can cram some 33s on it...

 

I changed my stock 17 to stock size 20. When I stood the wheels and tires side by side the over all size was exactly the same. Due to that no reason the have computer messed with

 

Correct, the diameters are almost exactly the same and you shouldn't have a problem. IF you do have a problem, take it to your local dealer. There is a setting in the BCM they can change with the Tech II to compensate for the tires. Shouldn't cost more then about $35/$40. Again, this is only if you have problems.