Vehicles sinking into the ground

I'm working on a vehicle and when I use the Buggy tires on it, it works fine. I tried to replace the buggy tires with a bike tire. It's the same radius, but it's a lot thinner. Now when I go into torque, the wheels sink through the floor and the mesh starts bouncing on the col-1 mesh. What am I doing wrong?

I've made sure to keep the same multi-res options and it's linked up the same way as the old tire was.

Would it be something to do with the pivot point?

Release 1.1.2