What Should The Temperature Of Your Racing Car Tyres Be?
If the temperature of your racing car tyres are out then you are, at best, leaving free performance on the table. At worst, you are left wrestling the bear of all racing cars.
No racing driver wants to be driving a car that is trying to kill them.
What they want is a racing car that has loads of grip from the moment they leave the pits, to the moment they return.
The temperature of your racing car tyres influences how close you can get to that aspiration. So what tyre temperature(s) should you aim for?
Tyre Temperature, Grip & The Contact Patch
Tyre temperature effects the grip level and handling balance of your racing car because of how it effects the ability of tyre contact patch to grip the road:
The tyre contact patch is the part of the racing car that touches the road. All forces go through the contact patch so it is important to get it working well for you.
A racing car tyre grips the road through a combination of mechanical and chemical properties.
The mechanical aspects are maybe a bit easier – the harder you press down the more grip you have (to a point.) Have a read of my article on tyre side slip angle to get more of a feel for the mechanical grip aspect.
The chemical one I find a bit harder to get my head around. The best analogy I can think of is to think of it as a less extreme version of chewing gum stuck on your shoe:
The chemical grip comes from the rubber in the tyre literally sticking (briefly!) to the road surface.
I know enough about tyres to know that I am no expert on tyre physics. However my understanding is that the tyre temperature has the most influence on this chemical grip aspect.
A tyre’s grip level varies with tyre temperature but not in a consistent way. I think about how the grip level changes as being something like this:
At one extreme, too cold and the chemicals in the rubber make it go rock hard. You have no grip and feel like you are driving on ice.
At the other end, too hot and the chemicals cause the rubber to kind of melt like chewing gum. Like before, no grip but this time it is because the rubber has no internal structural stiffness and it is pulling itself apart.
Neither extreme is where you want to be.
What you are after is to get the tyre temperature somewhere in the middle – a temperature that gives you the most grip for the least degradation …
Race Car Tyre Degradation
Degradation notionally means “wearing out.”
There are different types of degradation (or “deg”) that you may hear talked about.
Here I’m taking a broad brush approach and simply defining degradation is a “loss of grip over time.”
The time is important. It could be a short time, say a one lap qualifying blast, or a long time, like full endurance stint at Le Mans.
Like grip level, the amount of tyre degradation changes with tyre temperature. Again, here is a chart below of how I think about it:
Some tyre degradation happens at all tyre temperatures.
Unlike grip, tyre degradation typically increases with increasing tyre temperature – all the way towards that chewing gum scenario where the tyre can pull itself apart … (eek!)
The Tyre Temperature Window
You might hear people talk about “getting the tyre in the window.”
What “window” means is range.
Here the “operating window” means getting your race tyres working within that optimum temperature range of not too cold and not too hot – a temperature range where you have good grip but not excessive tyre degradation.
Data On Your Tyres
Publicly available data on these tyre temperatures windows is scarce (as far as I am aware …)
As a result you will need to conduct some controlled experiments on your own tyres to understand how they perform.
To get you going, the table below shows some generally held advice on what temperature levels affect grip levels and degradation.
General Advise On Tyre Temperature, Grip Levels & Degradation
Use this table as a baseline template that you can then reference and adjust when you get your own test data:
|Temp (℃)||Grip Level||Degradation|
|65 – 75||Medium||Low|
|85 – 90||High||Medium|
|90 – 95||Very High||High|
|> 100||Medium > Low||Very High|
Combining this general data with my charts gives the chart below:
You can hopefully see that this “model” can be very useful to you in terms determining what should the temperature of your racing car tyres be.
Your tests will enable you to develop your own model of how your racing car tyres perform against temperature.
You can run specific test days for this or the easy route is to just to start gathering data and observations anytime you run and compare this to the general baseline above.
Discover Your Race Tyres Character
It is likely that the shape of your charts of grip levels and tyre degradation lines will be a different.
These shapes define what is sometimes known as the “character” of the tyre – like its personality.
Consider how the character of your tyre will be different.
Perhaps your tyres will:
- have more consistent grip levels across a wider temperature window?
- have a peak grip at a lower tyre temperature?
- maintain more grip at a higher temperatures?
- have no noticeable degradation at any temperature?
- still have degradation but with a less aggressive effect on grip levels?
You can decide to make this as involved or not as you choose. With tyres costing a significant amount of a racing budget however it is worth paying attention to tyre temperatures and trying to define your tyres character.
Even if the model remains in your head you will be better off and as a racing driver aware of this, you will know how your racing cars grip might be being effected by tyre temperature as you drive your stint.
Using The Data
Once you have your model here are two ways you can gain from the data.
1- Stay out of the Angry Bear Zones!!
Firstly is a general check that all your tyres are operating in the overall operating window.
If even one tyre is out that will have a big effect and your racing driver will in all sorts of trouble. Knowing the the temperature state of the tyres will help you in deciding your next steps to fix your issues.
The second way is more strategic. This is where you can try to optimise the compromise between grip and deg, depending on the nature of the session.
For example, in a qualifying session you want maximum grip. As quali lasts only a short time, the degradation becomes less of an issue so you can aim for slightly higher tyre temperatures.
For races you might want to be more conservative. You want to have enough temperature to give you good overall grip but with a degradation that makes sense for your type of race i.e. short sprint race verses hour(s) long endurance race.
I have found the strategic side to be both interesting and comforting.
Interesting because with a good tyre temperature table you can plan and optimise how you run each session.
Comforting because when, say, the tyres drop off on your 3rd qualifying lap you (should!) know why.
Clearly I’ve not been able to give you single number for you to set you racing car tyre temperatures but hopefully you’ve now a fuller understanding of how tyre temperature can effect your performance and got some tools with which to develop your own answers.
Also, next time you hear professional racing drivers or teams moaning about not begin able to “manage the tyres” or that they have a very narrow “window” you will know what they are on about!
Best of luck.
Enjoyed this? Check out these other articles:
Want to take the guess work out of setting your tyre pressures? Try this article including a free calculator: https://www.yourdatadriven.com/how-to-set-your-racing-car-tyre-pressures-perfectly-every-time/
Wondering what the tyres are actually doing? This article should help your visualisation:https://www.yourdatadriven.com/tyre-slip-angle-explained/