Just bought 2005 GMC 3/4ton 4x4 DA. I want to put 285s on my stock rims. Does anyone now how to re-calibrate the computer? Will doing this void my warranty? How will this affect the odometer and will it cause the computer to throw codes?


Thanks JROB

Some dealers might recal. it for you, but from what I have been reading in some of these forums is that if your truck develops a engine problem, trans. computer problem etc. they will refuse to work on the truck from what some people are saying "Improper tire size" and flag you VIN until proper size tires are installed, all dealers will see the flaged vin. I personnal think its bull$hit for them to tell us what we can and cant do to our trucks after all its my money that I paid to get the truck and for someone to tell me what I cant do to my truck sucks but dont get me wrong yeah I can see if someone installs a 10" suspension lift and puts on 44" tires that it will void the warranty and I agree with that but something that minor in tire size is down right stupid. Edited by: 96vette

I don't think they are saying it will void the warranty, I "think" they are saying they won't work on it nor attempt to diagnose without the original tire and rim size that came on it. The different size's throws off the diagnostic equiment.

I put 285 on my 2004.5 soon as I drove off the lot. I have not had any codes show up. i dont know about the taking it in to get worked on. as far as mileage it will be off roughly by about 50 miles every 35000 you drive if even that much. From the factor (of course) the computers are set for 245.

you probably dont have anything to worry about in all seriousness - everyone puts on different size tires and dont seem to have any problems with warranty work. Hell, i have a 4" Lift with 305's and have brought mine in 4 times now for warranty work, all done without anything said - and its going in tomorrow for injectors and a new egr unit

I did the same thing drove from dealer lot right to a tire shop and put 285x75x16 d rated (and carry more wt than E rated from factory). When tires were on went back to dealer and they reset the computer the best they could and still off by 2.5mph at 60mph. Not bad can live that. Only problem was little trim with front bumper and the zip tie the emergency brake cabel back. The ride really improved using only 65psi in tires and carry more wt. Which was really important to me. Warrenty wasn't a problem for them, they just made sure it fit in the wheel well.