[EricH]

I have three questions.
One, how are you going to keep from bouncing? You're driving along, and the roller edges hit the carpet coming around a 90 degree or so turn. Either you bounce, or you shatter the roller. Or maybe you shatter something else...

Two, how are you going to keep the rollers on? I mean, you can't just stick an axle through and say "stay" and have them stay on the axle. You need something hard on the outside, but how do you do that and not have to replace the whole tread?

Three, how much weight will this have? If it's too heavy, you might consider just wrapping the whole thing around a wheel for less weight.