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Tire Tech: Use A Durometer To Track Just How Hard Your Race Tires Really Are

All that hard work you put into your race car's chassis setup goes right down the drain if your tires aren't up to snuff. Using a tire durometer is one good way to monitor their capability to generate traction.

All that hard work you put into your race car’s chassis setup goes right down the drain if your tires aren’t up to snuff. Using a tire durometer is one good way to monitor their capability to generate traction.

Everything you do to improve your race car’s suspension. All that hard work you put in dialing in the setup. All those hours invested trying to get everything just right. It is all about maximizing the friction between the race track and the small contact patch at the bottom of each tire.

And when you depend so much on the contact patch, it only makes sense to ensure that the tire creating contact with the track is of the quality you expect.

Race tires usually come with a rating for hardness. Obviously, a softer tire will almost always provide more grip, while a harder tire will last longer. In racing classes with an open tire rule, it can become a game of finding the softest tire possible that will still provide hold together until the checkered flag flies.

But most classes have a rule that requires a specific tire, or at least a tire that “punches” no softer than a certain rating. The track or series will tell you which tires are approved for that rating, but you can check for yourself to make sure the tires you are using aren’t any harder than necessary.

A durometer is a tool specifically designed to determine the hardness of the rubber compound a tire is constructed from. At its most basic level, a durometer is simply a spring that pushes a pin into a surface. The harder the surface, the more the spring is compressed, which creates a higher reading on the gauge.

Keeping a durometer in your tool box can be handy for several reasons. First, never trust the manufacturer’s rating for a tire. Always check your new tires to make sure they punch the correct rating. As unlikely as it may be, you don’t want to hit the track that’s mislabeled or simply been a part of a bad batch in the manufacturing process. And if you are buying new tires, it can’t hurt to choose the softest you can find instead of just taking four off the top of the stack.

Second, wear and heat cycles can affect the hardness of a tire. Generally, they get harder through heat cycles and use. Even though the tire may still have good tread, it can glaze over which creates a hard surface layer. You can only know this by checking the hardness with a durometer. When you have a tire that’s glazed over, you can knock it off with a grinder to get back down to good rubber. If that isn’t allowed it’s time to use that tire for practice and get a new one for racing action. Otherwise, you putting yourself at a competitive disadvantage to the rest of the field.

Tires can harden, or even glaze over, with repeated heat cycles and wear. Keep a regular check on the hardness of your tires, and make sure to check the inside, center and outside quadrants of each tire just to monitor for uneven wear.

Tires can harden, or even glaze over, with repeated heat cycles and wear. Keep a regular check on the hardness of your tires, and make sure to check the inside, center and outside quadrants of each tire just to monitor for uneven wear.

If you don't already have a durometer in your toolbox, Jegs now has a good option that sells for less than sixty bucks. It registers from one to 100 in one-point increments, so it should easily cover most racing tires and has a large two-inch face to make it easy to see.

If you don’t already have a durometer in your toolbox, Jegs now has a good option that sells for less than sixty bucks. It registers from one to 100 in one-point increments, so it should easily cover most racing tires and has a large two-inch face to make it easy to see.

When punching a tire, the key to getting consistent readings to consistency. Don't simply bang the durometer into the tire. Instead, start with the durometer laid back and "roll" it upright onto the tire. The allows the spring to do all the work pressing the pin into the rubber.

When punching a tire, the key to getting consistent readings to consistency. Don’t simply bang the durometer into the tire. Instead, start with the durometer laid back and “roll” it upright onto the tire. The allows the spring to do all the work pressing the pin into the rubber.

If you look closely, you can see that this tire has been "needled" to soften it up. The process of putting thousands of small needle holes with a special tool helps a tire act softer than it's hardness rating. But when checking the durometer rating of a tire that's been needled, make sure to avoid the needle holes with the durometer pin. This can make it read softer and give inconsistent readings.

If you look closely, you can see that this tire has been “needled” to soften it up. The process of putting thousands of small needle holes with a special tool helps a tire act softer than it’s hardness rating. But when checking the durometer rating of a tire that’s been needled, make sure to avoid the needle holes with the durometer pin. This can make it read softer and give inconsistent readings.

 

Source

Jegs / 800.345.4545 / Jegs.com


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