1x1
1x2
1x4
i could do proportional sizes, but these don't really make sense to me lol.
Also, Christopher's idea is really great. But the thing is, you cant really put thise on cars, planes, etc. Because the way the collision box is makes it so that you can get an axle really close to the back side of the wheel.
i could move the actual model outside of the box a little bit, so that when you put a brick next to it, the tire is more against the brick.
also, is there a way to conveniently store models in one .blend without having to make multiple files for multiple bricks?