The Vex Tank Treads were designed and tested for rough surface “all-terrain” usage. They have limited traction on flat smooth surfaces, but their hard plastic teeth are designed to bite into rough terrain such as grass, dirt, or deep carpet. They are also intended to provide a means of building a robot for climbing over obstacles.
To get additional traction from the Vex Tank-Treads on smooth surfaces (hardwood, tile, etc) we recommend the following method. It is possible to glue strips of rubber belting onto each Vex trank-tread section. (In the groove on each strip.) We recommend belting similar to McMaster Part Number: 2126T1. Your mileage may vary.
To prevent tank tread binding, do not run treads overly tight. The design of the Vex tank treads allows for them to run with a small amount of slack, without derailing. Overtensioning these treads will cause additional friction in the tread rotation, and decrease the efficiency of the system. Also search out other sources of binding and inefficiency; reducing these will result in a much smoother operation.
At a National Championship for the FVC in Atlanta, we saw teams who glued rubber band strips onto their tank treads for added traction on smooth surfaces. Those looking to increase the traction of their treads can try this method or a one similar to this. Always verify what you are trying is legal if you are competing in a competition.