I like to check out the various Japanese micromouse builders’s site to see what they are up to. Google translations sometimes make some sense but it is very hard work. I was looking on this blog the other day: R & D daily: work out. The author (whose name I cannot work out – sorry) has a picture of his latest mouse sitting on a slope. The slope is at a very steep angle indicating the tyres may have a coefficient of friction with the maze surface of 2 or more. Pretty impressive. This particular mouse has four wheels. It is a wheelchair drive mouse but with two wheels per side. I would expect that to cause problems with the tyres having to slip around corners but so far it seems to go pretty well. Check it out. Look for the pictures and links to videos.