From our experiance last weekend at Lincoln, the bead lock wheel will pack with mud more then the standard wheel. We didn't make a cover, since we had thought it would be against the rules. We thought about it a lot and I figured we would not be allowed one. When we got out to the track they were on a lot of cars. We ran the heat without one and it was pretty packed when he came in. Didn't get the chance to find out how much got in there in the feature though as the right rear axle broke taking the green. Next time out we will have a cover on there though. Will be interesting to see what the tracks that don't allow covers will do with this. I would think INEX should allow the foam plugs in this case.