I have another question regarding this asignment. I've managed to model the spokes/rim of the wheel and the tire body using the solidify and mirror modifiers, but I'm trying to build the surface of the tire itself using the array modifier to replicate a plane along the circle path of the tire body (more or less the same thing Jonathan does with his column example), but somehow I end up arraying the whole system itself. I'm a tad lost on why this happens.. I'll keep digging anyhow