[JamesCH95]

Originally Posted by rwood359

The wheel doesn't but the carpet probably does. It seems like the larger wheel will have more contact area with the carpet.

Exactly, though Jared341's point is very valid. One can always use a wider wheel to get the same contact area with a smaller diameter wheel.

Originally Posted by LLogan

Well, a robot's acceleration (and thus pushing force) is caused by the force of friction between its wheels and the surface that they're on. The larger contact patch (larger surface area) shouldn't have anything to do with the torque because surface area doesn't matter for friction.

But, your team is the one who has tested this, and you have said that it helps, so I'm going to believe you.

In a simple HS and even College physics sense the contact pressure has nothing to do with the coefficient of friction because physics teachers like to keep everything nice a orderly, which is good when one is learning the basics.

HOWEVER, from my experience in race-car design I have had the opportunity to look at things like tire performance tests which clearly show an degradation in the friction coefficient as normal force is increased. Granted it wasn't a Skyway or Plaction wheel that was tested, but it was still a polymer tread surface and I believe it demonstrates the principle quite well.