Wheels

ky-kurnell · November 4, 2003

Hey Everybody, if Irun a 285/70/17 does it need reprogrammed, and does Chevy give you any hassles on warranty because of the bigger tires, if anyone has pictures of 17's with 285/70's that would be helpful, is there any clearance problems with that combo, my truck is a 2003 Z71 ext. cab LT.

Sorry for the tire questions.

Thanks Again

LogixRat · November 4, 2003

Seems alot of folks with the Z71 are runn'n 285/75's without problems. That in mind the height on those tires are roughtly 32.5" x 11.22". The 17" tires you are looking at trying to use measure out to 32.7" x 11.22".

That puts the tires at almost identical sizes, and my speculation is that you would be fine with the 17" wheels and tires. If you do get a little rub, you can do like so many others with 4wd and give the ole torsion bars a little twist.

Wingnut · November 4, 2003

Yeah....That.

And the stealership will not be able to correct for that large of a tire unless they have changed something VERY recently.

Only way to do that is with an aftermarket ECM, or ECM tuner.

LogixRat · November 4, 2003

If you don't already have a programmer, and don't feel like plunking down the $$ right now for one, visit the following site to enter the original tire sizes and the new ones. It will calc the differences and at the bottom will also tell you how much your speedo will be off. Keep in mind, this reading is approximate and will be lower when you drive slower and higher when you go faster.

http://www.miata.net/garage/tirecalc.html

RobtZ71 · November 4, 2003

I just threw on some 305/70-16 GY MTR's on my 2000 Silverado yesterday with no problems. I did have my torsion bars cranked several months ago. There still seems to be plenty of room. I wish I had some pics.

Ben · November 4, 2003

First off, what truck ratings? GVWR and front/rear GAWR. That will tell what type of truck and min ratings for wheels/tires.

In Europe/Asia it's against the law to put lesser components on a vehicle. Min is what came from the factory and is listed on the manual. Fines, license suspension and even jail time for the shop owners/managers. Ditto for the owners of the vehicle, regardless whether they knew or not.

Another thing is how you use your truck. If mainly "car", then P rated will be fine. If hual/tow heavy, even once, best to go to LT rated tires and wheels with higher ratings (wheels have weight and pressure ratings). Even the valve stem should be rated accordingly (all rubber are usually maxed out at 44-50 psi, all metal is rated 200 psi).

GM has been tough on tire dia larger than OEM for Duramax/Allison because it can break stuff if it doesn't know what sized tires. Shift points in normal and "tow/haul" mode is based on the computer look up tables and those tables are part of the programing (aka tuners, etc). ABS is also affected, as the ABS computer has it's own look up tables that tell it when the tire is about to skid (lever arms), and skid doesn't necessarily mean stopped rotating...skid can be just couple rev's slower than what it should be at 80 mph.

Just wanted to note this, as there's lots of comments, but worried out of context. Out of context if those P rated tires & wheels are going to be put on a 1500HD/2500/2500HD/3500 truck.