These have been a great pullley to use for driving wheels on a dead axle setup. On 1519, we have used these pulleys with either 6' or 8' pneumatic tires on our 2016, 2018, and 2019 robots, and have never had a single pulley failure or problem. We bolt the pulleys directly into the wheels via the 1.875' bolt circle and typically use three 1/2' round bearings on dead axles, placing 2 bearings in the wheel and 1 bearing in the outer side of the pulley. They work great!