RE: wheel hexes
They are 17mm, at least that's what came stock on my Monsoon XTR. Also I might suggest considering getting them fom Traxxas if your going to be purchasing them. My reason is, at least for me I've found many more wheel options from Traxxas compared to Redcat. The hub is different between the two companies. The pin on the Redcat hex will not allow a Traxxas wheel to be used. The Traxxas wheel is more like those newer style Craftsman wrenches where the wrench bites the sides of the nut instead of the corners. Same goes for the Traxxas wheels. I'm on my second set of factory Monsoon wheels. The torque is murder on the inner hub of the Redcat wheels. I've also managed to split two of the rims and I really don't bash my Monsoon.