Highest traction wheels

[JamesCH95]

Originally Posted by MICHAELABICK

I believe some of your statements are incorrect. Usually, the only variables that affect traction are coefficient of friction and weight. Because wider wheels just mean that the same weight is spread over a larger area, you have the same amount of traction. This is different when roughtop tread and carpet interact, because the roughtop "locks" in witht he carpet and increses the amount of traction you have with wider wheels. This is also like drag racing, where they heat up the wheels so that they "stick" to the ground and wider wheels have more traction.

To answer the OP's question, I have heard that colsons have the most traction on flat surfaces.

Physics teachers the world over repeat this simplification. It is not true in real life. Coefficient of friction is a function of contact pressure for every traction system I've seen, namely coefficient of friction increases as contact pressure decreases.

There have been a number of tests done by forum members/teams indicating the wider wheels provide more grip with the same normal force... however I haven't been able to find the posts mentioning this yet.

Originally Posted by Michael Hill

I think there are a couple of misconceptions here. There contact area will actually not be increased by that much with a wider wheel. It sounds odd, but the pressure that would be applied over a thinner wheel is now spread out over a wider one. That lower pressure doesn't allow the tread to expand as much along the wheel. However, because your width is greater, the contact area is roughly the same.

Second, drag racers have wide tires solely because of heat. You need big tires to dissipate it all. The stickyness that happens does, in fact, increase traction because it now brings in adhesion (your coefficient of friction is now >1). It literally is pulling the car down when this happens. However, in our situation, our wheels aren't producing near enough heat to do any of that.

Another thing to remember is that friction is very inexact. It's been seen in some circumstances that the coefficient of friction can change with respect to load (which goes against classical friction theory). There may be many other factors that come in to play as well.

You're making a simplification here, heat is not the only reason to use a wider tire/wheel. Wider tires/wheels allow for the use of softer tread compounds that might wear too quickly on a narrower wheel by virtue of having more material available to wear away.

A wider wheel/tire will generally have a contact patch with a more uniform pressure distribution than a narrower wheel/tire due to the wheel's/tire's structure's effect on the contact patch. The wider wheel/tire can thus generate more grip because the coefficient of friction is a function of pressure, and the wider wheel/tire has a lower peak pressure in it's contact patch compared to a narrower wheel/tire.

I suspect that the analogy of car tires to typical rigid robot wheels fails at one important premise: rigid wheels do not maintain the same contact area vs width because they do not have a controlled contact pressure (i.e. tire pressure). Thus a wider robot wheel could very well have a larger contact pressure.

This is the theory I've learned and experienced with race car design/driving and some FRC teams have demonstrated through testing robot wheels.