Tires do sit inside the rims, but have a bulge, maybe they were trying to reproduce that?. Buy a tube of "Flex Seal" and paint those tires. They will look like real rubber tires. You can glue strips before you paint them and when you paint the tires, the glues will looks like treads. In this case, you would build. In this case you would build two flat thin (in gauge)paper strips for the outside edges and 3 thin (in gauge) and in width for the inner treads. This would make the tires have grooves. It's an excellent effect, really takes the car over the top.