I got my car tire mounted on my 650. The only way was to sand the rim down. I took the wheel to a machine shop, after some discussion they dedcided they would not do it because of liability issues. Turns out i am glad they dedcided not to. I decided to do it myself. Dan (Danson trikes) and i had no luck at tire dealers and motorcycle shops getting the tire mounted, it would not kick out. At first we felt the safety bead was keeping the tire from going on, so we grind the safety bead off. I wasn't too concerned with the safety bead as the trike does no real leaning in curves, and the trike is supported by 2 outer tires. I used a palm sander and mounted the tire on 1/2 in conduit in vise. vibration from sander caused the rim to rotate as i sanded. I sanded with about 8 sheets of course paper paying particular attention to the rise from the center part of the rim, i felt this is really where the tire was hanging up. Took the tire to a friend of mine who owns tire store, and i would not seat. Took rim back home sanded some more, still wouldn"t seal. Sanded some more, i guess I used about a dozen 4 1/2 x 51/2 sheets of 50 grit wet/dry sandpaper in all. Took it back to my fried and it sealed. Yesterday Dan and I put the wheel back on test drove it. I drove for a small test run, i loved it. seems to improve traction and braking as far as i am concerned. Dan had up to 80 said it did fine.