More Wheels?

[Chris Fultz]

You don't really get any more traction with 5 vs. 4 wheels.

Surface area is not part of the equation.

From our friends at Wiki -

Maximizing multi-wheeled vehicle traction
It is important, due to broad application, to point out the specific case of multi-wheeled vehicles or vehicles with multiple contact patches between the tire and the road surface. Multiple wheels do not increase a vehicle's traction, because the friction force is independent of the contact area.[1] The friction force (Ff) is dependent upon the coefficinent of friction (COF) between the contact surfaces and the normal force (N = a force perpendicular to the contact surface).

Ff= N(COF)

A greater number of wheels will allow a vehicle to carry a larger load, thus increasing the resulting normal force. More traction is achived with a greater load because the potential frictional force has been increased.

The case of wheels sharing a given normal force is particularly important in vehicle design. Two identical tires sharing a common load achieve maximum stability when they share the load equally. Likewise, an unequally loaded pair of tires sharing a common load will not be able to achieve the same maximum stability.