5" run 17mm ID Bearings.
7 and 8" wheels require bolt on hubs with bearings if running on a stub axle. Or keyed hubs if running on a moto axle.
These are Go Kart Rims
Blue axle is 8" stretch
Pic with front and side view and black pipe is 7" stretch
Red Axle is 7" stretch
Black axle is 5" (no stretch)
Note PVC is grey/white, PE is black (out of stock)