Since 2016 we advise the owners that changing wheel size will mess the spedo. The dealership can adjust only if you have oem and do not need reflashing but they need to get their computer to change sizes. I have 22 all around so there is no way to adjust. The other way around is that you get with someone that have a computer and the time to make an over lay that can be place over the spedo. You will need to open it and stick the new decal inside. You most run with someone inside the SS to check speed on SS and GOS to get the right number and let the guy know what changes need to be done.
Speedometer calibration
We have a base model 2018 that came with 18” wheels all around. We upgraded to factory 18/20” wheels from an SLR. Our speedometer is off by about 5 mph at 75mph. The local dealer says they can’t “reflash” the ECU to let the vehicle know the wheel size changed. Has anyone had their dealership do the reflash? If so, can you provide me your dealers’ contact information? I want to get this done, as it is annoying to have inaccurate speedo readings since we do Turo rentals. *
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