I would complain about the price, but a set of spare wheels (tubes and tires) costs almost the same. I can buy a new Dolly from Harbor Freight for the price of spare wheels. Anyway, this is the way. Prices are similar to standard bikes. Replace them and never have to replace them again. When mounting on a cart, make sure the metal rod (aka spindle) is long enough. I bought them for an elderly neighbor with an older car. I had to "set" the wheel brake calipers with a hammer to install them and insert pins to hold them in place. (I still think they're overrated)