i just put 305/70/16's on my 05' duramax diesel crew cab,and the dealership said they could not change the settings to fix the speedometer from being off..... is this true? am i out of options? or are the techs at my dealership mistaken? they said the computer would hook up to it but would not change the settiings because the allison trans could not be changed.

they will only change your ecm to read 265x75r16 which is on the one ton single axel trucks. Buy any programer and it will adjust for tire size , do some research before you buy, there are lots to chose from, just be carefull extra HP is more addicting than sex or drugs

. . . just be carefull extra HP is more addicting than sex or drugs

:funnypost but very true :ro)

there are a number of tuner's that can adjust the tire size for the speedo: Predator, Quadzilla, Hypertech, Superchip ? ? ? also, Super Lift makes a box to mount under the truck that allows you to program and then switch between two different tire sizes (look on-line or contact a 4x4 shop).

My dealer was going to reprogram for my 35" tire size for $100 :mad:

I got the Quad and you can change tire size by .25" increments. I used the GPS on the highway and found I needed to make one more adjustment by just that amount.

i also have a 02' silverado 1500 that has 285's on it.... will those programmers work with both of my trucks the 02 1500 and the 05' 2500 duramax diesel