Heat Dispersion and Heat Cycles.

You’ve already heard a lot about things like heat cycles, heat dispersion, grip, contact areas, and the like. When browsing through all the materials one thing became clear, they were all incredibly technical, and they only covered one topic at a time. The truth is, they are all related, and all that information should be in one place. So, we did the legwork and did it for you. If you want to know how heat dispersion affects grip, tire life, and why heat cycles are important, you’ve clicked on the right link. Congrats, on picking the commonsense breakdown on heat dispersion.

Heat dispersion, what is it?

To put it simply, it’s how heat generates inside your tire and disperses. We all know tires get hot, we burn ‘them’, and move on. However, understanding how and why they “burn” will give you insight on how to maximize the use of your rubber and get the most life of them.

Heat builds up in your tire mainly because of two forces, hysteresis, and tire-road interaction. That’s enough of this science talk, we aren’t the science guy.

Basically, hysteresis is the expanding and contracting of your tire as it contacts the road/ track’s surface. Because of how fast you’re shredding corners, your tire doesn’t have time to release all the energy that your tire builds up from contracting against the road before it contracts again. This translates into a buildup of heat. Hot, right?

So, what is road-tire interaction? Glad you asked, its friction. Friction is created as the tire slides along the roads surface. This can be caused by drifting around corners, or simply by turning your wheel, breaking, and accelerating. Any time the tire is moving on the road’s surface that isn’t directly proportional to the rate of spin, you will create excess friction, and that creates heat.

The good news is that heat is energy and energy must go somewhere. Your tires will transfer that heat back out to the road, the air, and your wheel. This will keep your tires from completely burning up, if you’re smart about how you drive them, if you keep running them past their optimum performance temperatures, they will start to deteriorate. Depending on the application you’re using them, this isn’t necessarily a bad thing. Which brings us to our next topic.

Get grippy

Whether your drifting corners or running the track, one of the most important considerations to make when looking at tires is the grip factor, aka treadwear.

There are an actual TON of factors that affect your tires grip, but one of the most pivotal of them being the way your tire heats up and interacts with the asphalt below it.

One of the main factors that influence grip is called, indentation. This is caused by hysteresis, because like mentioned before, the tire can’t return to its original shape before contacting the road’s surface again making an asymmetric formation. This creates a force vector with deformities in the road’s surface that opposes slippage, providing you with that sticky grip you need.

If your operating on a tire like the Accelera 651 Sport which utilizes R-Compounds, they have a very specific window of temperature that provides peak performance of the tire. This is because of the tire is too cold, it becomes rigid and doesn’t create the indentation needed to get the grip you want.

However, you can get the tire too hot, and it will start to blister and fall apart right under you. Think of your tire as little Goldilocks, she can be a little finnicky with the temperature, but once you got it right in the comfort zone, everyone is happy.

Knowing what this window is, and knowing how to get there, and maintain it, is the trick. Some tires can have an optimum window of performance as small as 5°C.

The other main component of grip is molecular adhesion (I know I promised to cool it on the science-y stuff, but we need talk about it). Think back to tenth grade chemistry, and how molecules bond with one another. That’s what happens every single time your tire touches the road. The molecules in your rubber love the ones in the road, the grab each other and hold tight… that is until your rip them apart violently (also why tires wear down so fast in these applications). As your tire reaches this Goldilocks zone, these molecules are really trying to connect with the others, giving you premium grippage. ← Yes, it’s not a real word, no we don’t care.

During wet conditions molecular adhesion becomes harder to achieve, because of the layer of water between the tire and the road. When using a tire like the Accelera 651 Sport that is specifically designed with lateral and circumferential grooves to break the film of water and create better contact with the pavement during wet conditions.

HOT LAPS

You track boy’s... and girls know all about the importance of a hot lap. The reason we do this is to get that rubber up to temp. Driver’s drive relatively sporadically in order to do this by weaving, accelerating, and braking.

Some drivers, depending on their application, like to begin with a burn out to create an abundance of friction to quickly heat up the tire. Because of road-tire interaction we know that these actions can expediate the heating of the tire, getting those suckers in the right window for optimal performance.

Contact patch

So, you would think this would be commonsense, but a contact patch is exactly what you think. It is the area of the tire that touches the pavement. However, we are going to break it down, so you know exactly what matters when we are referring to this area of tire.

The average contact patch for a car is roughly 137 square inches. This relatively area is responsible for controlling what direction your car goes, how steady your acceleration is, and how fast you can brake. So, making sure the contact patch of the tire is well maintained is incredibly important to the control of your car. For instance, if you over-inflate your tires, the tire will have a smaller contact patch, not providing enough traction, and less hysteresis. However, if your tire is under-inflated, you’re contact patch will be large, and uneven. Therefore, paying attention to the air pressure in your tires is as important as maintaining proper temperature, as they are inter-related.

What’s the Fuss with Heat Cycles?

After all of this about heat and temperatures it would be weird if we didn’t at least touch on heat cycles (even though no one ever does). A heat cycle is the process your tire goes through from going to an ambient temperature, then going to its performance temperature, and the returning to ambient temperature again.

The process of heat cycling warms up those molecules getting them excited and wanting to bond with each other (like we talked about before with molecular adhesion). Getting those molecules all revved is great for enhancing grip and enhancing the life of the tire. What becomes important here, is what your application is and how you need your tire to perform. As the tire cools back to its original ambient temperature, those molecules start bonding with each other, strengthening the bonds within the tire and making it less soft. This is great because it does enhance the length of the tire, but it does decrease the amount of grip after the first heat cycle.

Many performance tire manufacturers recommend scrubbing the tires, as opposed to running a full heat cycle. This entails running your tires for a shorter session (4-5 laps) and your cool down can be as short as 30 minutes as opposed to one to three days.  This will heat the tread providing you with the grip you need, without hardening the rest of the tire.

Our Thoughts?

Now that we have covered all that information, there is a lot to derive from it. We know that your tires are going to perform optimally while hot, but not overheated.  We also know that heat, makes your tires have better indentation and enhances molecular adhesion, providing you with better grip. Its also because of molecular adhesion that after so many heat cycles, your tires will harden and lose some of its grippy properties. Now it’s up to you, the driver, to take this information and use it to properly optimize your tires for your best performance.

Here at Tire Streets, its all about making everybody well rounded Race Ready.