tires voiding warrenty

[regcab02HD]

Does anyone know if installing bigger tires will void the warranty on my pickup.  I read on another forum that some dealers say your warranty will be voided if you install bigger tires than stock.

[Shaners]

I've heard this too, but I can't substantiate it.

 

I asked my dealer service mgr if he would reprogram my speedo for me if I were to step up one size, and he made no mention of it voiding the warranty.

[RyanbabZ71]

if you have an allison trans yes.  Well wont void the warranty they wont do any work concerning the transmission unless you put the correct size tires.

 

They cant void any warranty (like for example if you put larger tires on and you are having problems with your seatbelt they cant void it for that).

[RyanbabZ71]

there is a gm tsb out stating what i said about the allison trans and larger tires

[RyanbabZ71]

oh yea one last thing i promise

 

I took my truck in for the trans.  Around 35mph it was like the OD was locking up.  Tech took it out and i already had the latest software installed.  I had larger tires and they didnt say anything.  

 

This lockup did go away after a few months which was kinda wierd

[CMNTMXR81]

This question and many other warranty related questions get asked time and time again and my answer is always MAYBE.  Why?  Cause it's a "grey" matter.

 

Technically?  GM or a GM dealer can void your warranty at any time they wish if and when they see a modification done to your car.

 

Reality?  In most cases no, they won't.  If you modify your intake or exhaust and your power window motor goes out, the two are unrelated and as such, the modifications you did are irrelevant.

 

A lot also depends on the dealer and their service department.  In ours you could pretty much bring your car in still on E.T. Streets and skinnies with the blue bottle still hooked up and we wouldn't care.  Other Service departments aren't like that.  They see a cat-back system and they're already on the phone calling GM to void the warranty.  My suggestion is to talk to your favorite service department's manager and even the owner of the dealership and get their feelings on the matter.

 

On to your specific quandry though, no set of tires withing a reasonable size is gonna hurt an Allison transmission.  These things are meant to handle 12,000+lbs or weight, no tire 4 sizes bigger is gonna even make it flinch.  If something is wrong internally with it, something else is the culprit and would've given way regardless of what tire was on it.

[tinman]

I have 305 on the 99 sierra I have . I took to the dealer to get the speedo recalabrated(wast of time). And to look at the brakes. They tryed to blame my brake problem(over sensitive ABS) on the larger tires . While the had the truck in the did two racalls . The funny thing is that the brakes were all better after I got the truck back.   HHMMMMM very interesting.Anyways they never said jack about the larger tires affecting the warrenty.

[CMNTMXR81]

I have 305 on the 99 sierra I have . I took to the dealer to get the speedo recalabrated(wast of time). And to look at the brakes. They tryed to blame my brake problem(over sensitive ABS) on the larger tires . While the had the truck in the did two racalls . The funny thing is that the brakes were all better after I got the truck back.   HHMMMMM very interesting.Anyways they never said jack about the larger tires affecting the warrenty.

Your Wheel Speed Sensors (WSS) on each reluctor that the ABS system uses to compute potential lockup is calibrated in the PCM/BCM at the stock tire size parameter as is the Vehicle Speed Sensor (VSS) in the PCM.  It computes that by taking the vehicle speed per the factory tire size, that the tires should be revolving at "X" amount of rpm.  It then compares this amount with what the individual WSS's feed in and determines whether or not a potential lockup is at hand and therefore engaging the ABS if needed.

 

So in essence, your dealer is correct, by going up to a larger size tire, 305's in your case, your WSS's are reporting back slower readings to the BCM and could potentially trigger the ABS system sooner in a panic stop or slow speed stop.

[tinman]

I understand that the brakes would be affected by the larger size tire . But this truck was unsafe . The dealer did nothing to compensate for the larger tires. The just performed the recall or update now the truck stops fine . There a couple of devices out there that will compensate for the larger tires. The speedo is only about 5mph of and the brakes are working great now. So in summation the tires weren't the problem. The truck had a defect. My point was that the dealer seem agitated that the truck had larger tires but never mention anything about voiding the warrenty. The  dealer also said they didnt have a code to compensate for the larger tires. They still charge me 40 bucks for trying to find a code.

[RyanbabZ71]

I got charged $18 after a wk prior the shop foreman told me they could reprogram it.  Tech spent 20 min on the phone with gm and it was a no go.  They wanted to charge me $36 but i argued saying they told me it could be done.  We came to an agreement at half.

[tinman]

I wish I could bill a cutomer in my trade for talking on the phone and not fixing anything! :0

[kanton1]

Ryan and Others,

 

The TSB for bigger tires and the Allison tranny is only for the Duramax and its problems with staying in overdrive when using cruise control. The Big Block with the Allison doesn't fall into this catergory.

 

Also, Hypertech and others make the HPP III as you already know, which will recalibrate. It will not recalibrate for the Allison yet, GM has not released the codes.

 

Lines about how the dealer cannot recalibrate for bigger tires is a joke, GM gives (sells, whatever) the calibration codes to the Aftermarket (Hypertech) for this purpose. On the programmer I had for my '96 Yukon and my '00 Silverado I could program for tire sizes up to 34" and gears of 4.56.

 

Good Luck,

Kyle

[CMNTMXR81]

I understand that the brakes would be affected by the larger size tire . But this truck was unsafe . The dealer did nothing to compensate for the larger tires. The just performed the recall or update now the truck stops fine . There a couple of devices out there that will compensate for the larger tires. The speedo is only about 5mph of and the brakes are working great now. So in summation the tires weren't the problem. The truck had a defect. My point was that the dealer seem agitated that the truck had larger tires but never mention anything about voiding the warrenty. The  dealer also said they didnt have a code to compensate for the larger tires. They still charge me 40 bucks for trying to find a code.

Just pointing out the technicalities.