Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

SlickWillie · 05-20-2010, 08:51 AM

I went to a little bigger tire on the 04 Duramax 2500HD. The LT245/75R16 tires just looked small to me. Moved up to the LT265/75R16 and the speedo was not off enough to worry about. You don't have a gear on the speedo to change out. You just need to get GM to adjust for tire size in the truck's computer. Or, you can buy one of the tuners that will let you do it yourself. I had a Diablo Predator for the 04 Durmax, and it had that feature. You just select your tire size, and bingo, it corrects the speedo.

I thought about one other thing after Skypilot posted. The LLY Duramax engines (04 & 05) were prone to overheat issues when towing heavy. I did notice a lot more fan activity on my 04 after going up in tire size. I never had the overheating issue, but our rig isn't that heavy, and I've never been out of TX or LA.

05-20-2010, 08:51 AM	#2
SlickWillie Montana Master Join Date: Dec 2006 Location: Posts: 2,376 M.O.C. #6575	I went to a little bigger tire on the 04 Duramax 2500HD. The LT245/75R16 tires just looked small to me. Moved up to the LT265/75R16 and the speedo was not off enough to worry about. You don't have a gear on the speedo to change out. You just need to get GM to adjust for tire size in the truck's computer. Or, you can buy one of the tuners that will let you do it yourself. I had a Diablo Predator for the 04 Durmax, and it had that feature. You just select your tire size, and bingo, it corrects the speedo. I thought about one other thing after Skypilot posted. The LLY Duramax engines (04 & 05) were prone to overheat issues when towing heavy. I did notice a lot more fan activity on my 04 after going up in tire size. I never had the overheating issue, but our rig isn't that heavy, and I've never been out of TX or LA.