Understanding Durometer Readings

Durometer is one of several measures of the hardness of a material. Higher numbers indicate harder materials; lower numbers indicate softer materials.

Hardness may be defined as a material’s resistance to indentation. The durometer scale was defined by Albert Ferdinand Shore, who developed a device to measure Shore hardness in the 1920s. The term durometer is often used to refer to the measurement as well as the instrument itself. Durometer is typically used as a measure of hardness in polymers, elastomers, and rubbers.

Shore’s device was not the first hardness tester nor the first to be called a durometer (ISV duro- and -meter; attested since the 19th century), but today that name usually refers to Shore hardness (other devices are simply called hardness testers).

sooooo, let’s boil down what these means to you, a tire consumer and why durometer readings are incredibly important to engineering tires specific to unique terrains, vehicles, load ratings and air pressue (psi).  To make things easy, a reading of 1 is extremely soft, 100 would be extremely hard.

The term “Durometer” means both the measuring tool, and the unit of measurement. You use a durometer to check the tires durometer.  Generally speaking, a low durometer tire will stick better, and give better traction. But it wears out faster. As a tire heat cycles and wears out, the durometer rises.

The durometer is extremely heat dependent.  As tire compound (rubber) raises in temperature, it becomes sticky. This is important to consider because checking the durometer readings of your cold tires in your garage more than likely  will not alter the readings.  Checking your tire durometer readings directly after use or in direct sunlight in temperatures over 70 degrees may affect your readings.  Trust-worthy tire manufacturers will openly supply durometer readings however all technical specs are based on cold compounds in temperature controlled environments.