Coefficient of friction of wood vs metal

[Jen Lawrie]

It will depend a bit on what type of wheels you've used. As an example, AndyMark's 8-in pneumatic tires reportedly have a CoF between tire and carpet of 1.27, compared to the CoF between tire and steel of 0.49. The link below lists some CoF values. There could be a significant difference.

http://www.andymark.com/product-p/am-0972.htm

[MrForbes]

We had to do some work to our chassis to get over the rock wall, after adding a layer of sheet metal to the top of it. Remember the ramps are also made of plastic....not plywood...