i have a set of these i have not got to test out yet, but they are a crazy tire size and even when they are mounted on the rims look like the bead isnt set on all the way. they seem to be a skinnier tire then normal 10" wide tires and thats why they look like the are not set on the bead. can of starter fluid and a match works wonders for any tire that doesnt want to go on the rim. BANG there on there that was the only way i got mine mounted. i believe i bought the 20/10/9 but truely they look like 19/9/9 bought them to try something different instead of changing gearing on mx track.