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View Full Version : Speedometer calibration on a Sierra



Tom Brown
07-27-2007, 10:56 AM
My Dad has an 04 Sierra. He tells me it came with 235 tires but the previous owner put 245 tires on it. His speedometer is out by 10%.
Can this be easily calibrated? It sounds like they don't use the little nylon gear in the transmission anymore. I assume it's a digital strobe. Are we going to have his computer reporgrammed? Can a dealer fix it?
Thanks

Jordy
07-27-2007, 11:13 AM
No more nylon gear in the tranny tail shaft... all electronic these days. The dealer should be able plug into it and change the ratio/circumferance/flux capacitor so that it reads correctly. :D

Daytona100
07-27-2007, 12:23 PM
Or you can get a reprogrammer and reset your tire size. Hypertech etc. Mike:D

Tom Brown
07-27-2007, 01:10 PM
Thanks, gents. :cool:

goneboatin
07-27-2007, 05:58 PM
No more nylon gear in the tranny tail shaft... all electronic these days. The dealer should be able plug into it and change the ratio/circumferance/flux capacitor so that it reads correctly. :D
You can adjust your flux capacitor with any old Mr. Fusion.

Beer-30
07-27-2007, 07:53 PM
235-what to 245-what? That number is only the width. What was the original tire size 235/?? and what is the new 245/?? and on what size rim? 16s? 17s? It may not be off by much at all.

IMPATIENT 1
07-27-2007, 08:12 PM
any local gm dealership can recalibrate the tire size, it only takes 2-3minutes to do it. the new body style trucks(07-08) can only have the tire type changed at the dealership cause the general told us they didn't want people changing from stock sizing(increases what the general pays out on warranty repairs).