I've been working on and off for over a year to find a way to replace old Kenner SSP Racer tires as the original 45+ year old rubber is shattering due to the fact that when I take these toys to church, a new generation of kids is literally running the rubber off the rims. Part of the problem is that the original rubber was molded directly onto the pot metal rim when it was made. I was trying to find a way to make a tire that could be pulled over the rim. I have a possible solution, but I have to acquire more materials to test the theory. In the meantime, I have achieved some success using a modified version of the original production process. The picture shows (L-R): Original rim/tire; Original rim with the broken remnants of an original tire; original rim, no tire; original rim, new tire.