Wayne i wish it could be of more help, but i'm not much of a mechinac. Because I had a friend who could try to mount the tire, is why i sanded a little at a time. It took me 3 times before i got it to seal. The way i measured it the auto tire was 2/16th less on the inside bead than the cycle tire. If i had to guess i would say i removed less than 1/16th from the rim. When Dan and I tried to mount the tire the first time we were putting up to 80 lbs in the tire to get it to kick out, but it would not. We felt the safety bead was the problem. So we grinded the bead flat to rim, but it still wouldn't kick out. When i started to to sand the rim the palm sander would just fit inside the rim, so i guess i was sanding down the whole inside of the rim as it went around. After a couple of tries the guy putting the tire on felt it was being held in the center of the rim. So when i started sanding i tried to round the edges so the tire could get started. I would say that is the key. once you look at the rim you will see what i mean. however i do feel it would be necessary to sand some of the inside rim itself due to the smaller size of the auto tire. my way of thinking is the removal of the safety bead is not a issue with me because it's a trike, the scooter will not be leaning in turns, and you have 2 outer wheels for support, i fell if something happened i would just lose traction and braking on the rear, as you know most braking is in the front. I would not be doing this if it was not a trike. If I ever go back to 2 wheels i would have to get a new rim. If anyone tries this they should somehow mark the inside of the rim that it was altered and should not be used on motorcycle tire. I don't know if this helps, but this is all i know
bob