I have a new 2005 GMC 2500 Duramax 4x4 full load to pick-up this week.

I want to swap the 245/65/R16 tires off to either 265/75/R16 or 285/75/R16's. I asked the dealer if they can recalibrate the truck for the new tires and they have told me that the 245 are the only supported tires. Is this true and will I screw up my warranty if I put the larger tires on?

I have also heard that the Duramax has had problems with the front-end going, is this true?

SCOTTLand

You will not void the warranty by putting on bigger tires.

Buy a Hypertech programmer or some other power programmer that will
re-calibrate your speedo
I had 285/75r16's on my 01 and never had a prob at the dealer
http://memimage.cardomain.net/member_images/6/web/498000-498999/498786_12_full.jpg

My Avalanche and Duramax both have BFG 285-75-16 tires..The spedo difference is only 5mph and I did not make the change with the predator programmer. This means you put a few less miles on the vehicle.

If you take it in for warranty work they will not diagnose unless the original tire size is on the truck. Plenty of post on here about the subject. So no, it won't void the warranty, but they wont go any further if it's related to the drive train.

Depends on the dealer. Mine has no problem whatsoever.

I believe the 2005 3500HD single rear axle truck comes with a 265/75/R16 tire. Assuming that is correct, then you should be able to make the argument that the 265 is also a supported size.

Thanks for the responses.