Warranty and larger tires?

[SLT556]

I just picked up my 05 Duramax and the 245's are dinky to say the least. Will I void my warranty if I put 265's on it?

[tanker]

Good question, I would sort of doubt it, as my new 05 K-3500 will be equiped with the 265's, however the 245's go 681 revs per mile, and the 265's go 654 revs per mile which may or may not fool the computer. I'm sure a dealer could recalibrate the computer for that size tire, but knowing how conserative GM is about certain things :rolleyes: I'd check with a good GM dealer, and let them find out. Let them show you where it is written. ;)

[More Power]

SLT, I agree that GM should offer a larger tire.

GM service centers were issued a service advisory some time ago informing them that they were not to provide drivetrain related warranty service on 2500HD/3500 series trucks unless equipped with the factory tire size. I feel this is being really short-sighted, but many dealerships are not enforcing this rule - to the letter.

I'd recommend discussing this issue with your local service manager. Most would be willing to work with you.

If you do install larger tires, I urge you to get the vehicle speedometer corrected. You can do this using any one of several aftermarket programmers, like Predator, Hyper-Tech, BullyDog, and others. For those with an LB7, you can also use a "Tru-Speed" calibrator sold by Super Lift (http://www.superlift.com). Aside from tire size adjustments, I recommend a programmer for many other reasons as well, like reading codes and displaying a huge amount of engine/drivetrain data. I'll have a product review available soon on the Predator.

I find it interesting that owners of the C4500/5500 equipped with a Duramax/Allison can get their dealer to alter the factory programming to correct for larger tire sizes or even gearing changes, without a fuss.

MP

[PONCH]

SLT566
When I bought my 03 dmax my dealer suggested that I switch to 265's. I drove straight off the lot to a michelin dealer and switched tires. I am going 2 mph faster than indicated, so I didn't mess with the programer.
Technically I guess the switch would make this a one ton with the added weight that the tires will hold 300lbs each or so.I put on the LTX M/S 265's and love them.
SEE YA BYE

[SLT556]

Anyone have pictures of their truck with 275's or 285's?

[royalglen]

good luck putting larger tires on 05-I installed 285 18" on an 03 First day but removed them after approx. 2000 miles- could`nt turn steering wheel on dry pavement.Also was afraid of bending control arm(tie rod).Find glossy brochure from GM with Wheels available from GM.Wheels are warranteed- is the truck?My truck is Duramax 2500HD

[4diesels]

The GM party line is that they will not diagnose some issues if larger tires are fitted. However as mentioned it really depends on the service dept. If you just bought a $40k truck from them most are good enough to ignore the larger tires, its a good idea just to aske them. Technically they can't deny warranty coverage unless they can PROVE the change you made caused the failure. Chances of that are about zero.

I ran 265s on my '01 for the 97k miles I owned it. I used it for towing heavy goosenecks and the added load capacity was nice to have, and the look is MUCH better. I also ran 285s on my '03 from new. Niether dealer I took it to ever mentioned anything about bigger tires when it was in for warranty work, which was more often than I cared for :( One note is that the 285 D range carry the same load as the 265 E range (or very close) and do it at a lower pressure (65 vs 80) for a little nicer ride. I never had bad wear issues with either size, just keep them rotated.

I would go for it! That and a set of Bilstein shocks really transform the ride and handling of the truck.

[More Power]

As a point of interest, we see more complaints about fuel economy from people who install larger tires. In most cases, this drop in fuel economy is due to a combination of the speedo being off and the various computers not having the correct info to properly manage the powertrain.

The standard reply to low fuel economy complaints is now to first get the speedo corrected, then report back. Methods to accomplish that can be found further up in this thread.

MP

[TanM998]

tire size can be calibrated by anyone with a tech 2. Its really not very hard to change the tire size in there...