I think you hit something hard enough to break Tokamak's collision and imbed the tyre in the road. I can't really see any way around that apart from making it break the wheels off if you hit something hard enough, which would then mean either continue on 3 wheels or reset.
I'd say breakable parts to the cart would be wicked guaranteed that it only occurs under extreme circumstances, actually managed to get another tire stuck in the road doing what Becky was trying to do. The fact the tire got stuck that way kind of worries me though, it was nowhere near as hard an impact as that last vid I posted.
(got any other maps with some really "extreme" jumps I could screw around on?)
VirtualDub kept crashin on me for some reason using XviD compression this time (got no better plugins for it at the moment), but I managed to get it working under high compresison rate.
http://media.putfile.com/scr3
Also got another vid I captured the other day, where I rode the car along the side of the road for the whole beginning of the course up to the actual first jump. Might upload it if I get bored enough.