These wheels, which are standard on the Equipe R2 Skate Rollerski, are made of fast polyurethane composition for speedy skiing. Rather than changing `wheel speed`, the different polyurethane wheels change through skiing conditions. The softest of the wheels is the Yellow wheel with a hardness rating of 76A. This wheel is best used by lighter athletes in wet conditions and rougher asphalt. The next wheel is the Orange (78A) which is the most average condition wheel, good for wet or dry. It is the standard wheel that comes on the rollerskis. The next hardest wheel is the Green (80A), which is best for heavier athletes in rough, dry conditions. The hardest wheel in the lineup is the Red wheel (82A). It is best used by heavier athletes on dry, smooth roads in hot weather. All these wheels are sold complete with standard or ceramic bearings The Equipe R2 wheels are all special order as we do not hold them in stock. Order them sooner rather than later! Wheel dimensions: 100mm x 24mm (the same as all the other popular Swenor Skate rollerskis).