Just about ready to pull the string on a set of Moto Metal 955 Rims with 285/60/18 Nitto Terra Grapplers to replace the stockers for summer. I am looking to see what problems I might encounter with these larger tires if any. What will the larger tires do to the speedo and shift points. What will need to be adjusted or trimmed. Will the dealer be able reprogram so the speedometer reads correctly.As the Sig says bone stock 0 turns on the T bars.Thanks in advance for your help.

Cranked my bars about 2". Put BFG 285's on. Speedo compared to a GPS is about 3 mph off. If I put the cruise at 67, the GPS says 70. The radar dummy for the school crossing says the same as the GPS, so I'm thinking it's about right. Can't tell any difference with the shift points or anything else.

You'd have to crank your t-bars and might have to do some trimming of the lower plastic on the bumper and maybe some of the plastic on the back of the wheel well liner. And you may have to tie back the brake cable behind the wheel liner on the driver side. I don't think a dealer can reprogram for tire size b/c they will go back on the use of bigger tires if something goes wrong with the tranny, rearend, or motor. You can get a programmer and add a small tune and change your size through it. A small tune might help with some mileage too.

Any more thoughts guys?????????

I have 285/60/18's on my GMC. I only had to cut the front valance a bit to get the tires to clear. On the Chevy you might not have to cut anything if the backspace is correct, maybe just a crank or two on the t-bars. I fixed the speedo with EFI Live.

You'll love the look of your truck after you put them on!

I have 285/65R18 tires, which are a little taller than the 60 series, on 18x9.5" rims with like 6" of BS and I have ZERO turns of the torsion bars. I had to trim the corners of my lower valence and back of the wheel well liner but thats it. I have no rubbing issues. I actually did all that trimming for 285/75R16s on 16x8s with 3.75" of BS. There are pictures in my garage of how close the tires are to touching but they don't rub with either the 285/75R16s nor the 285/65R18s.

You'll love 'em!!