A torus is more expensive than a sphere, true, but if you have two of them in your entire scene, you’re not going to see a difference. Even if you have ten bikes, each with two torii, the extra computations needed to collide a torus compared to a sphere are unlikely to ever show up on a profile.
The main challenge would ge that Chaos by default doesn’t support toroidal colliders, so you’d have to write and plug that into the engine yourself…
But, colliders aren’t seen by the user. You can cheat! You can use a thin box or convex hull that’s slightly smaller diameter than the wheel itself, and not perfectly round, but then also a smaller sphere at the bottom to get the “rounded” collision.