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View Full Version : Tires and the computer


ChopperBill
08-13-2002, 21:59
Took my new "03" GMC D/A with only 70 miles on it and traded the 2.45 tires for 2.65's. Went down the highway the following weekend and set the cruise at 65. Pulled out the GPS and it said I was going 67. I called the dealer a couple of days later and asked if the puter needed something done to it and he said for 30 bucks they can program for the bigger tires. Great. Had it done. Went down the road after they set it up, same thing speedo 65, GPS 67. No difference. I went back they hooked it back up and showed me where it was set for the 2.65's. They couldnt tell me why but will check it out when I come in for my first service. Any comments on this I have never had a speedo show under the correct speed before with only one size change. I went up two sizes on my other GMC and it made the speedo spot on with the GPS.
pepperidge
08-13-2002, 22:04
chopperbill,

Could they have possibly just recalibrated the ABS for tire size?
This is the only calibration available for larger tires.

IMHO go get your 30 bucks back. They should have done this for you complimentary anyway.

Hope this helps,
ChopperBill
08-13-2002, 22:28
Going to ask for the 30 bucks back if they didnt do any good. Dont know much about auto puters but heard that it was going to around $300 to get it re-calabrated. Guess I thought $30 was cheap but then again I didnt get nothing did I? :rolleyes:
pepperidge
08-14-2002, 08:25
ChopperBill,

You did get the ABS calibrated to your tire size. That is something... I'm not so sure in real world testing what that would do but in theory it is supposed to make your ABS work to the best of it's ability. I'm not saying you didn't get anything for your money. I was just saying my dealer did this for me for nothing. This was done while my truck was in for all the updates anyway and I got to watch the Tech do it. It is done in the ABS section of the Tech II handheld.

I'd still get my money back as they did'nt do what they told you they could do for the 30 bucks.

Good Luck,

P.S. HEY MACKIN I"M STILL HERE!!!
Kennedy
08-14-2002, 08:59
Yes, the only part affected was the ABS. I run 235's and have found (dyno) that the speedo is just about 1mph short at 60. Close enough for me...
JimWilson
08-14-2002, 09:32
You paid what, 40 grand or so, for a new truck and they nickel and dime you for $30?! Even if it did work I'd tell them to go scratch. What a joke...