I have an older (approx. 1988) small Lawn Chief riding mower with a flat tire. The tire (tubeless)actually came off the rim after I tried using Fix-a-Flat. The tire seems to go back on the rim fairly easily but it's loose. When I push the sidewall in I can see the rim and the tire can be pushed off the rim. I guess this means that the bead is not sealed to the rim. I can't take the wheel off (it doesn't have lug nuts like a car tire). It did have a strange looking clamp and washer that I was able to take off but that's as far as I could get. It looks like the end of the axle is attached to the rim. Any suggestions?