The wheel durometer describes the hardness of the wheel. The durometer is usually the second measurement stamped on the wheel or wheel packaging, followed by the letter "A". A wheel marked as "76mm/78A" will measure 76 millimeters in diameter will have a hardness of 78A. The larger the durometer number, the harder the wheel, and the harder the wheel, the longer it will last – but a hard wheel gives a rough ride and provides less grip on your skating surface. The smaller the durometer number, the softer the wheel, and the soft wheels grip much better and ride smoother but don't last as long.Choosing a Durometer for Your Discipline
Durometer ratings do not go over a 100A rating. Recreational skate wheel durometers are usually in the 78A to 82A range. Indoor skates are typically 72A to 78A and outdoor skates go from 80A to 84A. Inline skate wheels with high durometers are used for aggressive skating, and their durometer measurements can go into the 90s. It is not necessary to match the durometer of all wheels on your inline skates. A mixture of wheel durometers can result in a combination of surface grip and a smoother ride for speed skaters, figure skaters and aggressive skaters.Your Skating Preferences
Most seasoned skaters choose to ignore all of the rules and assemble unique wheel durometer combinations based on their own wheel experiences, skating goals and personal styles.