Q: What is durometer and does tire compound matter when buying tires?
A: Durometer is the hardness of cured tire rubber. Tire hardness impacts how well the tires grip, how stiff the knobs are in terms of flex they give, as well as how fast the tire rolls and how long it lasts. Clearly tire impact is important and understanding it can help you the buying process.
How is tire compound determined?
Tire hardness is checked by using a Shore A Durometer named after maker Albert F. Shore. The hardness is checked by a needle that penetrates the rubber and reads the hardness on the dial. Mountain bike tire compounds generally range from 50-60 for all-mountain tires, 60-70 for XC tires, and 40-45 for downhill tires. The harder 60-70 compound is referred to as a standard rubber hardness.
What you need to know about tire compounds
- Tires with softer rubber (40-55) puncture more easily but have better traction. Softer rubber tires tend to have thicker casings though, and thus tend to be heavier.
- Dual-compound tires use a softer rubber on the sides, for better cornering, and a harder rubber rubber down the middle, for better durability, braking, and acceleration.
- Ignore people in the forums that complain of durability issues with racing tires. Educated riders purchasing race tires with high-tech casing and compounds are after the greatest traction at the lowest weight. There is no such thing as the lightest tire on the market, with the best traction, and the longest wearing. You must choice your priorities when shopping for tires.
There are many other factors to equate into your tire buying decision, but tire compound should be one. However, tread design, casing (TPI), tubes or tubeless, riding style, tire size, and riding location (types of trails) should also be considered when buying new tires.