Polyurethane is superior to rubber in resistance to grease, oil, cutting, chunking, and abrasive wear. These caster wheels can be used on almost any factory floor. As with moldon rubber, the bonding agent which holds the polyurethane tire ( tread ) to its iron center can be affected by exposure to some chemicals, impact, overloading, and the buildup of heat. Tire hardness is 90 to 95 Durometer, Shore A for wheels with prefix PY, PYR and PYC. Tire Hardness is 60 – 65 Durometer, Shore D for wheels with prefix PYH. Temperature range is -20° to 180° F. The principle benefit of a polyurethane wheel over the same size rubber wheel is increased capacity. Given the same size load on a smooth floor, a polyurethane caster wheel rolls easier than the same size conventional rubber caster wheel. However, when used at full capacity, polyurethane is not easy rolling. Given a manual operation under ideal conditions, polyurethane caster wheels have a safe operating capacity of up to three times the capacity of the same size rubber wheel. Capacity ratings are offered as an idea of what the wheel will carry without failure. They are not absolute, but rather depend on the usage and service.
Your conditions are almost never ideal, so select a caster wheel with much higher capacity than the weight you require. Polyurethane is not truly floor protective because it lacks the resilience and cushioning effect of soft rubber. However, polyurethane is less damaging to floors and cargo than “hard tread” wheels because it provides some tire deflection under load. Polyurethane caster wheels are not recommended for storage (standing) loads except for wheels with prefix PYH.
Wheels with PY and PYR prefix are popular for most polyurethane wheel applications. Wheels with PYC prefix have a slight crown to the tire ( tread ) which enhances the ability of a swivel caster to change direction. Prefix PYH designates Extra Heavy Duty wheels. They have extra thick iron centers and tires. The 60 – 65 Durometer tires provide higher capacities for extra heavy duty applications.
Wheels with prefix PX have a Premium Polyurethane Tire molded to an iron center. They are our highest capacity polyurethane wheels with 1″ Thick, 95A Durometer tires. Premium Polyurethane Tires provide a lower rolling resistance at higher loads and buildup heat more slowly in a power-towed application. Do not use any polyurethane wheel in a constant rolling application.