I ordered a big one. They are still about an inch or more from contact with my wheels. I see that a guy put a tree on it. I'm not sure how well the wood makes contact with the tires. I will buy rubber seals. But what a pain to modify my garden camper. I think these things are a good product and they performed well in an unbiased video comparing them to expensive metal products. It would only be nice if those in charge considered such a direct question before entering the market.