I put 265's on my 05 2500HD and took it to the dealer to recal the spedo.......what they ended up doing was recal the abs module for the new 265 tires.......did they recal for the abs or for my spedo? Anyone know?

I'm running the Michelin LTX's and they are GREAT!

my stock truck was off by 3mph according to the gps unit. i then added 265 and had the dealership recalibrate for them. when i check the speedo with the gps it is still off by 3mph. i sometimes wonder if they really did anything or just took my money. im interested in the answer to.

I went from 245's to 285's and I had a performance tune set for 265's on the truck(gasser). With the 285's and GPS my speed is dead on. I think that a lot of these trucks set a little fast from the factory. I bet that a set of 265's on a stock Duramax will make the speedo be more accurate than it is now.

This has been an ongoing problem with my '01. At an indicated 70mph,

my GPSr shows I'm actually going 77mph. Had it back to the dealer early

on with my then-265/75-16's and they Tech II'd it. Nada. No change.

Took my money. No answers. Stealers...:mad: Now with my 285/70-17's I am

about two more mph off; higher. Sure, it makes my odometer run slower,

but I have other uses for my GPSr I'd like to doing. I thought about using

a programer like a Quad or other that provides a recal and speedlimiter

change but I understand they don't work on an '01 model truck for this

function. Same for the SuperLift TruSpeed (and I guess it throws ABS

codes...?). So, I'm still using my GPSr to watch my speed and calculate

my milage. I'd really like to know what will work to correct my speedo

without having to endure another trip through the stealership. I am also

using early Edge box, version 4.31; without the Attitude. Makes no

difference with or without the Edge on speed indication (as it shouldn't).

Sorry to hijack the thread, but I would like to see a viable answer here.

Thanks for your time.

Brock in Montana...

i just started running the mich ltx a/s in 265's too. but i'm 265/70/17. i'm not certain the height difference between ours if you are on a 16 rim, but i think it's close. i just put 3,500 miles on in the last 2.5 weeks. as for the tire... i am so happy with it. very quiet, and rides like a magic carpet. it made a world of difference in towing (coming from 315 bfg!). some have complained about how it handles in the rain, but they have put a new tread pattern on it that is supposed to make it be a good rain tire, so we'll see what happens this winter.

the way i check my speedo is on the interstate over a long stretch using the highway markers. over 100 miles, my 265/70/17's were off by 1.5 miles (odometer reads low). so basically, at highway speeds i'm going about 1 mph faster than my speedo. that is more accurate than the stock setup. when i had the 315/70/17's on, it was off by 11 miles over 100 miles.

when i had 265/75/16's (not michelin... some off brand), i think i was 1 mile off over 100. so... i think you are real close.

just checked an old post of mine. the 265's on 16's were less than a half mile off over the course of 100 miles. the rollout difference between 245 & 265 should be about 3%, so maybe the stockers are off by 2.5% from the factory? gm sets them fast? i've heard that all the mfgrs do this.