You can get those at Harbor Freight for $1.99 each.
I can see using them for serious hardcore burnouts or donuts on pavement because they are so cheap.
You cold cut them for treads on the back pretty easy.
$1.99? Wow, what a deal.
RAC air tire kit ( May be the only Baja 5B's around with air tires ) see the tire valve in the pictures , nice , can be changed back to the HPI tires and wheels also if you want