We used 4 of these bearings in each of 3 expensive spoke-wheels on a SuperMileage car. When we first put them in man you could spin the wheel once and it would spin forever - we thought this would be the ultimate low-friction application for our supermileage car. But we got worse mileage with these bearings than the ones that came stock with the original wheels. The car with passenger probably weighed 250 lbs - really thought that 12 bearings would handle this for at least a while. We were extremely disappointed for the price paid.