Tire Size

[cdiddy]

Have a 2001 1500HD, not sure what the stock size is but when I got the truck it had 265 on it. Just put a body lift on and went to a 35-12.50-17 tire. I think the stock tire size was 245-70-16. My question is do I need to recalibrate or flash the computer?? And if so what exactly will that do???

[GM-Tech]

Having the proper tire calibration will mean your speedometer will register accurately, your trans will shift at the appropriate time, etc. ABS should be recalibrated to and this is in a different area. Calibrating the PCM does not do anything for the ABS.

[GM GIMP]

I changed tires of my 02 1500HD and used my Hypertech Programmer to re-calibrate for the difference. Unlike some programmers, my Hypertech asks for tire measurements rather than size. This make it more versatile IMHO.