Step 1 – Plug up your RTD Interface and your laptop to your vehicle.
NOTE: You will be using VCM Scanner BETA (not the RTD Flasher or VCM Editor) for this procedure, so open up that too.
*If you have not downloaded the VCM Scanner software, you can do so by clicking here.
Step 2 – Connect to the vehicle by clicking on the Connect to Vehicle icon.
Step 3 – Click the Vehicle Controls & Special Functions icon.
NOTE: If you get an empty window and do not have the option for the adjustment, click here for instructions. Complete that process, then continue on from here.
Step 4 – Inside that box click on the Speedometer tab and select Speedometer Adjustment.
Step 5 – The software will show the vehicle's current stored axle ratio. If this value matches the axle ratio installed in the vehicle, just click “OK”. If this value does not match the vehicle's current axle ratio, input the correct value and click “OK”.
Step 6 – Enter the new tire size. If you do not know your tire Revs Per Mile or Diameter (the software can show either), click here for a calculator that will do the figures for you. Tire Size Calculator
If there are any other prompts, just click “OK” on them. That’s it. Done!
