A significant measure used to evaluate the cushioning ability of any solid or polyurethane-filled tire lies in the “durometer” of the tire. For solid tires this would indicate the hardness of the rubber compound and other components used in construction of the tire, and in the case of filled pneumatic tires, in the polyurethane material that fills the tire cavity.
Most solid rubber tires are manufactured with a two or three stage construction. They typically have a tread durometer of 65 and higher, with inner layers at higher durometer levels. Many solid tires have added aperture holes in an effort to try and reduce the negative impact of a harsh ride performance.
Polyurethane-filled pneumatic tires, on the other hand, offer a wider range of core durometers from 8 to 55, allowing the customer to tailor the deflection of the tire for the application. Additionally, the pressure the polyurethane fill is installed at can be specified to match the application requirements. Thus, polyurethane-filled pneumatic tires provide the operator many options to modify the tire’s deflection capabilities, either decreased for a more comfortable ride where desired or increased where greater stability is required. Solid tires, in contrast, offer a very limited choice in deflection.
Polyurethane filled tires absorb more g-force vibration, reducing both driver fatigue and equipment stress. Heavy duty equipment operators seek as smooth a ride as possible. These operators often prefer polyurethane-filled tires, as the comfort and handling characteristics of polyurethane-filled tires are more comparable to those of air-filled tires. Because tire fill is available in a variety of durometers, it provides each piece of equipment with the operating characteristics appropriate for each application.