How can the air get underneath it? Maybe the old ones that had a screen rear panel would fill up, but mine has no opening. At speed it tucks nicely behind my lowered Silverado with a topper (cap). It wasn't a problem towing this car on it from Northern Minnesota to south of Phoenix. (A couple thousand miles in 2 1/2 days) It likes 60 lbs of air in the tires and it's best to have weight in my standard-cab, short-bed, 2wd pickup. To tow it with an empty truck or small SUV, you'd want trailer brakes. With a heavy truck, you can stop it.