Switching from 17 to 18 tires - Folks, wanting to switch from OEM 265/70-17 to OEM 265/65-18 tires/wheel combination. The local GM dealer is telling me the computer has to ...

Folks, wanting to switch from OEM 265/70-17 to OEM 265/65-18 tires/wheel combination. The local GM dealer is telling me the computer has to be re-calibrated or the truck will not shift/run right. Unfortunately, since my truck did not come with 18 inch tires due to the 6.2L engine/tow package, the dealership will not re-calibrate the computer. Sounds like a crock to me, but I do not want to give any excuse not to cover the warranty. Any suggestions? Thanks, Elvira

There's only a 0.1% difference in size between the two tires. It will not change anything and your speedometer will still be correct. They are full of it, unless you went to a larger/smaller diameter tire, then nothing will change. The only difference between the two is the 17's have more sidewall and the 18's have more rim.

Thank you so much! I got 4 new tires and 18" inch wheels for $1200 plus tax and hoped it was not too good to be true. Thankfully, not!

No problem. Post up some pics, and now you'll have to reset the wheel sensors with the truck, but that's an easy task and is outlined in the the manual.

Will do! Thanks again!

Your Dealer is really FOS. Makes you wonder about their automotive abilities in other areas. Look the chart I have attached and you'll see that the difference in OD is .2".

http://www.tirerack.com/tires/tires.jsp ... &tab=Specs

I basically did the same thing, only my truck came with 17s and 245/70/17 and I switched to 18s and to keep the OD the same I went with 265/60/18.

Lou

Thanks, Lou!!

Good grief, why in the heck would your dealer try and tell you that BS? I second what all the other guys say- you'll be just fine. And, if there is any change in the speedometer, you can either get it reprogrammed at a DIFFERENT dealer, or just buy a programmer yourself (usually $250-$300).

starspangled6.0 wrote: And, if there is any change in the speedometer, you can either get it reprogrammed at a DIFFERENT dealer, or just buy a programmer yourself (usually $250-$300).

But, that's the point - THERE WILL BE NO CHANGE!!!!

Lou

i went from 265/65/18 to 245/55/22 (both OEM)and called while at the dealer for another unrelated issue asked if i needed to get anything reprogrammed and they told me no.