Contact patch

Solid wheels also exhibit a contact patch which is generally smaller than the pneumatic “footprint”.

Since the wear characteristics of tires is a highly competitive area between tire manufacturers, a lot of the research done concerning the contact patch is considered highly proprietary and, therefore, very little is published on the subject.

Because pneumatic tires are flexible, the contact patch can be different when the vehicle is in motion than when it is static.

For example, a 10% change in load or inflation pressure usually does not result in a 10% change in the contact patch area[3] because the load or pressure on a tire can be altered freely, and the contact patch area is affected by the tire geometry and stiffness.

The contact patch of a railroad wheel is much smaller than for pneumatic rubber tires; it is only about the size of a dime (252 mm2).