What is a durometer rating?
Durometer or Shore durometer is a standardized way to measure the hardness of materials like rubber (elastomers) and plastics. Durometer measurement scales range from 0 to 100 but there is no such thing as a durometer unit of measurement.
Durometer numbers simply represent a relative comparison of hardness between different but similar materials that have had their hardness measured using the same durometer scale, device and measurement standard. In general, a higher durometer is harder than a lower durometer.
Shore hardness or durometer is actually a collection of internationally recognized measurement standards based on Shore durometers. Shore durometers themselves are measuring devices that use specific, standardized techniques for measuring hardness. Shore hardness standards provide a consistent, universal, easily reproducible reference that anyone can use to compare material hardness.
The above is a simplified graphic representation of a durometer hardness test. The arrows represent the applied load or force the Durometer puts on the material.
Notice that there are significant differences between the two shapes of the indenter tips. Type A indenters (left) have a 35° cone angle and Type D indenters (right) have a 30° cone angle. Type A indenters have a “truncated” or flat tip that is 0.79 mm in diameter. Type D indenters have a sharper tip with a rounded end that is 0.1 mm in diameter.
For all materials testing, hardness tests measure the depth of indentation in the material created by a given force using a standardized pressure foot or indenter.
When we refer to Durometer ratings on product specs for any Valor Offroad tires, we always use a Type A Durometer.
Material Comparison:
| Material | Durometer | Scale* |
|---|---|---|
| Bicycle gel seat | 15–30 | 00 |
| Chewing Gum | 20 | 00 |
| Rubber band | 25 | A |
| Door seal | 55 | A |
| Automotive/UTV tire | 70 | A |
| Soft skateboard wheels | 78 | A |
| Hydraulic O-ring | 70–90 | A |
| Pneumatic O-ring | 65–75 | A |
| Hard skateboard wheels | 98 | A |
| Hard hat (HDPE) | 75 | D |
| Cast urethane plastic | 80 | D |
