Need to turn off motion blur for my vehicle's wheels

You have several tricks to fix the problem:

  1. Limit the speed of your wheels rotation. At high speed, nobody will perceive that their rotation speed does not match vehicle movement.

  2. Instead of rotating wheels the common way, make them static and use vertex shader to do the rotation. If you also enable output of velocity for base pass and enable accurate velocity in wheel material, that opens up a possibility to accurately control motion vectors using PreviousFrameSwitch. The idea is to have a fixed wheel rotation lag for previous frame, that would not cause vectors to go wild. Of course this method has severe downsides, in regards to performance and usability, but it might be worth it.