How do you correct the speedometer for gears and tire size?
Here is what the documentation says. Each point links to its source; tables and names vary by computer, operating system and tuning software.
- GM; most GM vehicles up to 2018 model year: Changing tire size or differential gear ratio can make the speedometer, odometer, and transmission shift points inaccurate, so the vehicle needs gear/tire recalibration. (HP Tuners)
- GM; most GM vehicles up to 2018 model year: On GM vehicles, gear and tire changes are corrected with the Gear/Tire Wizard in VCM Editor, which recalibrates the speedometer and scales the transmission tables. (HP Tuners)
- GM; most GM vehicles up to 2018 model year: The Gear/Tire Wizard's Auto Scale option automatically adjusts transmission tables to preserve similar shift RPM after a gear or tire change. (HP Tuners)
More in the swap tune checklist, or build a checklist for your swap with the tune checklist tool.
Confidence: medium — sources disagree or are limited; check the sources below.
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Sources