Buy the blue ones , source them from andy email : accentgt8@gmail.com made from polyurethane a much stronger material thanrubber , iv'e had mine about 8mths and no movement what so ever , dont have to fill with innertube and wheelie better!
Google search them here to check out?

https://www.google.com/search?q=xt+6...MzR9O51j_EBvM: