Tire frame rate seems slower than vehicle when in slow motion

When I go into slow motion during play or recorded playback, the tire animation appears very stepped and much less smooth than the vehicles body animation. Are the tires animated at a different frame rates?

 

Nothing is animated, everything is simulated at 2000Hz, tires, wheels, and body included.
It's just down to how replays are saved. If you slow the game down instead you'll see everything has a sort of stepped effect