Wheels: Hardness & Sizes
The Roll-Line Urethane wheels, are incredible wheels which utilize Large, very Strong, & Lightweight Hub. This hub provides a thinner Tire Tread or wheel compound, similar in concept to a Low Rider tire on your car, and provides great GRIP and incredible ROLL, because there is very little or no Tread Compression, of the Urethane material as it heats up from friction with the Skating surface.
This combination of a very good Gripping wheel Compound, and a large Hub that provides the ROLL, and gives the Roll-Line Urethane Dance, FreeStyle, Hockey, Speed, or General Purpose wheels with wonderful characteristics of very Good Grip and Great Roll and a bonus of being Lightweight!!!
The Wheels have 2 numbers on them that count.
1. The Wheel Hardness is measured on the Shore scale:
Either on the “D” scale or the “A” scale
“D” scales are for hardnesses of Plastic Compound Wheels
“A” scales are for hardnesses of Urethane Compound Wheels
The lower the Number the – Softer the Wheel Provides More Grip with a little Less Roll
The higher the Number the – Harder the Wheel Provides a little Less Grip with More Roll
2. The Wheel Diameter is measured in millimeters
55mm and 57mm are used for FreeStyle skating, primarily. (the 55mm are based on a lowering of the center of gravity)
63mm are used for Dance Wheels, Derby and General Skating
63mm are used for the LARGE Figure Circles
61mm and 62mm are used for Hockey and Speed (are based on just a small lowering of the center of gravity)
60mm are used for LOOPS
The Hardnesses between the US and Europe do not exactly line up
US 101A would be most like a Grease 95A
US 103A would be most like a Grease 97A
Roll-Line most often provides 4 or more Hardnesses in each Style of Wheels
Most of the Roll-Line wheels, including the Grease wheels, offset the mounting of the bearings to the inside of the wheels, just a little more than some other wheels. This does provide a wider stance, which could be considered to help with stability like the old Pontiac Wide Tracking. Roll-Line Wheels have a little more space between the Bearings, when seated in a Wheel. The wider spacing is the same as the wheels of yesteryear. This allows for a little more stability within the bearings and not quite as much rotational torque, thus providing more roll than with the bearings spaced closer together.
Roll-Line believes in limiting the width of Wheel tread that contacts the Skating Surface, because too much wheel will cut down on the ROLL of the wheel. The use of a large light weight hub helps greatly with also increasing the Roll of the wheel. A large hub with a thinner tread minimizes the tire (or tread) compression that happens with most all Urethane wheels as they age a bit and works like a low rider tire on a car. Some Urethane Wheels have much more thickness (or tread) with a very small Hub, if any and after a time loose some of their Roll because of the heating from friction with the Skating surface and compression of the Urethane. Roll-Line uses a grippy Urethane compound in combination with the large hub, which produces a wheel with an unusual combination of Great Grip and Super Roll.
Other Wheel Notes:
Some of the low and mid level (and even some supposed high level) wheels come NEW with grooves in them, because as a part of the manufacturing process, they need to trim or clean up the wheel surface, so they lathe them, leaving the grooves. It also looks cool.
Grooves are not really such a good thing, as you are only skating on the tops of the grooves, or about 40% of the wheel surface. You actually get much better grip when you have more wheel surface contacting the skating surface. When the wheels are Bald, they are really performing the way they are supposed to.
As some wheel (especially the less expensive wheels) compounds age , they continue over time to cure or get HARDER. This harder result produces a wheel, which feels more slippery even though it has a low Durometer. Grooving a hardened wheel, means less wheel surface area contacting the skating surface and would be EVEN MORE SLIPPERY.