Go-Kart Tire Durometer & IRHD Chart

f you’re planning to read up on go-kart tire hardness, you’ve come to the right place. This chart indicates the durometer and IRHD readings for some of the listed manufactures and their tire models. Tire manufacturers measure tire hardness by the use of a durometer device or an IRHD (International Rubber Hardness Degrees) tester.

In the go-kart tire durometer and IRHD chart below, you’ll see either reading on the right side of the table. Please take note that go-kart tire manufacturers choose only one of the two reporting standards. Towards the end of this chart, you’ll also find a guide on how to read the durometer and IRHD chart and what each value means. If you would like me to add more tire brands and models or if you have more data to contribute, please get in touch with me and I’ll be happy to add it to this list.

Go-Kart Tire Durometer & IRHD Chart

How to Read the Tire Durometer & IRHD Chart

If you aren’t able to understand the durometer and IRHD chart above, then you can simply refer to the explanations below. I’ll go through each individual column and explain how to read their respective values.

Make

The make refers to the manufacturer’s name of the tire. There are many go-kart tire manufacturers, however not all of them publish data on the durometer or IRHD values. I’ve only included tire manufacturer’s who publish their tire hardness values. Below is a list of manufacturers that are featured on the chart. 

• Bridgestone
• Dunlop
• Hoosier
• Maxxis
• MG Tires
• Mojo
• Vega

Model

The model of the tire refers to the series. Most go-kart tire manufacturers group tires for a common purpose into a model group. To give you an example, the Maxxis Raptor model is a tire that is made for asphalt and concrete racing. A model would have multiple sizes, such as 10 x 4.50 – 5 (front), 11 x 6.00 – 5 (rear), 11 x 7.10 – 5(rear). Most of the time, the hardness of the tire model remains the same. On rare occasions, they can be different, but you will see this indication in the chart above.

Position

The position indicates if the tire is meant for the front or the rear of the go-kart. You’ll often see that rear tires are much wider than front tires. For example, a common front tire size is 10 x 4.50 x 5, whereas a rear tire size would be 11 x 7.1 – 5. Most commonly tire hardness of front and rear tires are the same, however manufacturers like Mojo have different tire hardness readings for front and rear tires.

Product

The product refers to the stock-keeping unit (SKU) or product number. Go-kart tire manufacturer’s often have a unique product code for each tire size in a model, so that you can make easier reference to a tire that you are interested in.

Dimensions

Each go-kart tire series or model has a few different sizes, each with its own product or SKU number. Each product number has a different tire size. For example, the Maxxis Raptor tire with the product code 85604 has dimensions of 10 x 4.50 – 5. I’ve created a separate guide on how to read go-kart tire sizes, if you are unsure on how tire dimensions are read.

Durometer

There are two standard ways to measure the hardness of a go-kart tire. The first way is to use a Durometer device. Durometer is an international standard that measures the hardness of rubber. Go-kart tires use the Shore A scale to grade the hardness of rubber.

If you refer to the values in the go-kart tire durometer chart above, the scale goes from 0 – 100 and the higher the number is, the harder the go-kart tire is. Sticking to the same example, a Maxxis Raptor tire has a durometer reading of 70 for all sizes in the Raptor model range. That means that these tires are considerably harder than the Maxxis Prime tires, as they only have a durometer reading of 48. That’s because the hardness of a tire determines its application.

IRHD

The second way to measure tire hardness is by the International Rubber Hardness Degree (IRHD) standard, which seems to be more commonly used by European go-kart tire manufacturers like Mojo (Germany) or Vega (Italy). In essence, they also measure tire hardness via a device which has an indenter.

Similar to the durometer scale, the IRHD scale also ranges from 0 – 100. The higher the IRHD reading of a go-kart tire, the harder the rubber is. Even though both scales are the same, durometer and IRHD values are not interchangeable. With that being said, please ensure that you read the values in the correct column.

Conclusion

I hope that you were able to find the durometer or IRHD reading for your go-kart tires. Please note that not all go-kart tire manufacturers have this available online, so if you’d like to contribute to the list, simply leave a comment and I will add it to the go-kart tire durometer and IRHD chart accordingly.

Tire durometer and IRHD readings can be different across models or position of the tire and the hardness of a go-kart tire usually indicates what type of tire it is. Rain tires, concession, sprint or racing tires often have a certain hardness to them. They also determine how long a tire will last and the hardness of a tire also has a direct effect on your racing performance.