They are designed for the alu wheelie bar wheels, but they also work on the plastic wheels. Check here.
Nobody is born with experience
Looks promising then! But the thread from above link is for Rustler-Bandit.
Even cheaper would be checking toy boxes of my kids ... I am sure there are some broken cars there that I could use as donors ... Maybe tonight ... when they're asleep ...
I have the bigger wheels on mine; just needed a small spacer on the shaft so they don't flop around side to side.