My pool cleaner wasn't moving very well and I was seeing tire wear so I ordered these replacements. Great price, quick delivery, easy installation. I was expecting an improvement but WOW! as if the whole block was new! As an engineer, I was curious as to why this improved things so much. What I've found is that as the old wheels wear out, neither the front fascia nor the rear fender slide on the underbody as intended because the gap becomes too small. In addition, the device itself begins to drag along the bottom of the pool, which not only wears out these parts, but also prevents traction from the wheels. miraculously works better. It's just silly not to replace them in time, and with the cheap price offered in the '2 sets' package (8 tires total), it's not only in terms of money, but in terms of that Money a good old deal how much better does your pool look with a properly working air purifier. LAW! This is the best money you can spend on clear and clean water in your pool.