the 12mm hex is correct, i really dont know the specifics of the stock tires. I use traxxas rustler rear rims, 4 of them. you may have to do a little trimming on the rims to make them fit, i have the stx and someone got some rims that were no good on the sv. The hpi 5 spoke seem to fit, these ones: http://www2.towerhobbies.com/cgi-bin...p?&I=LXM876&P=