[EricH]

Originally Posted by Bongle

My week-old QA interpretation was that anything you want can touch the floor, so long as it does not provide sufficient drag or thrust to affect the low-friction dynamic. If you coated the floor-contacting portion of your ramp with rover-wheel material, then it would certainly not provide any traction or braking beyond what you could expect with the wheels.

edit: I can't find the QA response that I had justified that in my mind with, ignore me until I find it.
edit2: Here's the QA response, which gives a pretty broad ruling:

You might read the most recent batch.

For example, there's this one, which pretty much bans slick balancing items, even if they won't affect the CoF.

There's also this one, which effectively rules that you MUST use the Rover Wheels for traction--having the same material on something else is illegal if it's used for traction.

They've tightened up a little bit. It's not going to affect many designs, I don't think, but it's enough to affect your interpretation a bit.