I did 38s on my hummer last week. I took it to the dealer yesterday for a few things it needs and asked them to do the 37in tire update. My speedo will be little off but not much compared to 35s and now 38s. They called me this AM said it would be $100 as they are charged for software by hummer. No big deal. Good news is that not only does it correct speedo for 37s but will raise the air suspension in all modes for the bigger tires. I have not rubbed in any right heights as it is now with 38s. I have not tried WTF mode driving but we did test just the height with 38s and WTF parked and no issues. Will share pics with new 37 software update and new raised right height. No idea how much taller it will be, as dealer did not know but will find out later today.
Here are some pics as it sits now with 38s and with factory 35in tire settings. First one is Normal mode or maybe high mode cant remember, then extract mode.
Here are some pics as it sits now with 38s and with factory 35in tire settings. First one is Normal mode or maybe high mode cant remember, then extract mode.