Do I need a retune after changing rear gears or tire size?
Yes, a recalibration. Per HP Tuners:
- Why: a tire or gear change throws off the speedometer, odometer and transmission shift points. Skipping it can cause poor shift quality, wrong mileage and trouble codes.
- How: on GM vehicles, the Gear/Tire Wizard in VCM Editor recalibrates the speedometer and scales the transmission tables. Its Auto Scale option adjusts the transmission tables to keep shift rpm similar.
- Coverage: the wizard supports most GM vehicles up to the 2018 model year.
See transmission tuning.
Confidence: medium — sources disagree or are limited; check the sources below.
Related questions
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- How do I add a real flex fuel sensor to an E38 Camaro and dial in E85 — what needs adjusting beyond enabling multifuel?
- What is needed to segment-swap a 4L60e E38/T42 truck to a 4L80E?
- Does simply selecting 4L80E under the transmission tab convert a 4L60E tune, or is a segment swap required?
Sources