pic: Basic chassis done

[RogerR]

Originally Posted by cinderblock

...So why extra wide wheels in the back?

one upside of having a large surface area is that the traction material will wear more slowly than a narrower wheel; more surface area means the forces are more widely distributed.

Also, while friction is not dependant on surface area, traction can be, under the right circumstances. for example, back in 2002 when you where allowed to lift 180# goals, teams would often tear up carpet fibers; the teams with narrow, high traction tires more than those with larger surface areas. by increasing the contact area, you spread the force around, so an individual carpet fiber is less likely to fail. more surface area, more carpet fibers sharing a given load.