The model is wrong. It doesn't have set Hub0 - 3 nodes, so it uses every vertex as a node. Either override ::onAdd to remove wheels (I'm assuming it's a Ball-style one) or make a new model.
However, if anyone has joined your server and downloaded the model they'll have to delete it/redownload - they'll still get Wheels errors.
It happens when you spawn the vehicle, not when it explodes.