Tunercat speedo calibration

[ShakerTransAm]

Does anyone else think that the tuner cat speedo calibration tool sucks?? I just can't seem to hit the nail on the head with getting my speedo perfect. I've punched in my tires, gear ratio, etc and that got it closer. Then I did the exact same thing again and got it closer but still not perfect. Anyone have any luck with getting it dead on? What's you're trick! Thanks, tyler

[firebird_1995]

I guess I can't say I've ever had a problem with it. Only thing I could say to do is actually measure your tires circumference and enter that instead of entering the tire size. Maybe that will get you closer

[JPack]

When I did it on all three of our cars, it was dead on with my gps. Never had an issue.

[ShakerTransAm]

Hmm that's weird. Maybe I'll start over. It's close but just a few mph off. I'll try measuring the tires too. Thanks

[bobdec]

For revolutions per mile try ' tirerack.com ' click tires by brand on the left side. If your tires are there click the 'specs' tab and rev/mile s/b listed. I used revs/mile and have not had any problems. Also have you tried the 'speed error' section of the TC speedometer tool. Enter actual and indicated and it should correct.. I never used it so can't verify the accuracy.