How To Measure Racing Car Tyre Temperatures
It might seem straight forward enough to measure racing car tyre temperatures, that is until you actually come to do it.
You know measuring tyre temperatures is important (hint: read this first if you are in any doubt) but how should you go about getting meaningful tyre temperature data?
The most meaningful tyre temperatures are going to be when the racing car is on track.
On track, you are likely to be trying to target a specific hot temperature to maximise your grip levels (see here for why) but how? How can you measure the temperature of a racing tyre rotating at high-speed?
In truth, you can’t measure the tyre temperatures you ideally need – but you can get close.
This article highlights some of benefits and limitations of the two main methods to help you decide the best approach for your own tyre temperature measurements.
Why Is Measuring Racing Car Tyre Temperatures Tricky?
Tyre temperatures cool in normal airflow and anytime they are not being worked hard on track.
As a result, what you ideally want to know are the temperature(s) exactly when the tyre is in contact with the road.
This poses two practical problems:
1- Temperature During Contact With The Road
Have a look at this picture of a racing tyre in contact with the road. The image shows the tyre pressing into the road, viewed from below (as if your screen was the road surface):
The image is actually a computer model of an old F1 tyre showing pressure distribution. However, if you imagine that the colour contours represent tyre temperature then that would be the ideal.
Unfortunately, when the tyre and the road are in contact there is no gap. This means no gap for any kind of temperature sensor. Even if you did add something it would interfere with the reading.
This means you can only measure the tyre temperature when the tyre is NOT in contact with the road.
You might be able to take a temperature very soon after but that measurement will not be at the point of contact.
2- Temperature Throughout Whole Tyre Construction
You want the tyre up to temperature but all of the tyre, not just the surface.
The other challenge is a tyre can be different temperatures at different parts of its construction. This effects the grip levels and means ideally you want to know the temperature inside the rubber. This inside temperature is referred to as the “bulk” tyre temperature.
A good analogy at this point is to imagine your best BBQ’d chicken that looks cooked from the outside but sadly is still raw on the inside.
In the same way that undercooked chicken is no good to eat, a tyre that has a large difference in “surface to bulk” temperature is not good either. In that situation, the tyre won’t generate high grip levels and is likely to also degrade (wear out) faster.
Like optimum BBQ chicken ( 🙂 ) for optimum tyre performance you want even temperature through the whole tyre construction.
Whilst you can measure inside the tyre bulk, you cannot do this (directly) whilst the car is on track.
Hopefully these challenges are now a bit clearer?
Despite what anyone may tell you, I thought it worth you knowing that you are only ever going to be able to get an indication of your “real” tyre temperatures.
But that might be enough to still be useful to you …
What Can You Do To Measure Tyre Temperatures?
So what can you do to measure racing car tyre temperatures?
Below are the two main approaches (with examples) to help you determine which route you are going to take.
One route does get close to being an ultimate solution, but remember, even the simplest approach is better than doing nothing …
2 Main Methods For Measuring Racing Car Tyre Temperatures
You can either measure racing car tyre temperatures using a pyrometer or using an infrared sensor.
1 – Pyrometer
The pyrometer uses a probe that you stick into the surface of the tyre when the racing car returns to the pits. It is similar to the food temperature probes that you can use to check your BBQ chickens’ internal temperature.
A typical motorsports pyrometer looks like this:
The temperature pyrometer allows you to measure the bulk temperature at a depth of about 3 to 5 mm below the tread surface.
This has the advantage of measuring the actual internal temperature of the tyre which (arguably) would give you the most meaningful tyre temperatures to work with.
It also takes you time to work around the racing car taking the measurements. This gives more time for the tyres to cool.
The issue is that because you need to stick a needle in the tyre, pyrometer readings can only happen in the pits. By the time the tyre is back in the pits, it has had the opportunity to cool – sometimes significantly.
The other disadvantage is, as with taking any readings manually in the pits, you are also going to have to separately record it and later combine it with your other logged data.
It is however the temperature you want. Many swear by using this method but you should know the drawbacks too.
2 – Infrared (IR) Sensors
Infrared sensors are non contact and use infrared radiation to determine surface temperatures.
They are clever bits of kit so here is a good technical explanation of how they work.
There are three main types of IR sensor you can use for measuring racing car tyre temperatures:
1- Handheld IR sensor
You can use a handheld infrared “gun” like the one below. This enables you to measure single point temperatures on the tyre surface when the racing car is back in the pits.
In researching this article, I also found this handheld IR temperature scanner. It seems to measure more points to provide a nice kind of tyre surface heat image:
These guns do have the same practical drawbacks as the pyrometer as you can only take readings in the pits.
Either way, these handheld devices are probably the most cost effective way for you to start measuring tyre temperatures.
2- External IR Sensor
You also have the option of two types of car mounted IR sensors.
Firstly with external IR sensors you mount them on the car and point them at the surface of your race tyres.
You need to be running a data logging system (that takes a fair bit of setting up) but once done tyre temperatures are logged automatically.
This is a real advantage as not only is that one less job for you in the pits, but the data you get is from actual on track driving so more meaningful.
Some systems log just one temperature where as others log a spread across the tyre. When combined with video the results look pretty good:
Whilst “more data is better“, the level of data is significantly more than the pyrometer or the handheld IR sensor.
Be aware, you might find it takes a little more time to understand it. Consider also that the wheels move relative to the chassis, they steer at the front and the tyre move relative to the wheel rim in corners.
Also remember that as with the handheld IR sensor, external IR car setups only give you surface tyre temperatures.
It is great data ( and makes good videos 🙂 ) but can be hard to interpret and there is a high chance you might get confused.
3- Internal IR Sensor
It is also possible for you to measure the temperature from within the tyre.
Rim mounted systems come as part of a tyre pressure monitoring system (TPMS) like this one:
Like the external IR setups, the temperatures are centrally logged on your data logger and the readings can be from a single point or a spread across the inside of the tyre.
For completeness, not all TPMS systems use IR sensors to measure internal “tyre” temperature. Many (most?) systems return an internal air temperature, or the actual temperature of the medal wheel rim. This data can be useful in approximating bulk temperature but as it is not an actual tyre temperature measurement I’ve not covered in this article. The considerations for you are similar to what is discussed below:
The advantage of the internal temperature measurement is that it is less sensitive so potentially easier to use. The idea is that it is closer to the bulk temperature you are able to measure with pyrometer. These internal temperatures are going to give you the most meaningful on track tyre temperature information.
The main disadvantage of these systems are that they need powering. Typically this is via a button style battery. Once setup they are reliable (most systems can handle tyre changes) but clearly ensuring the batteries have charge adds extra preparation for you. It might also be that you cannot easily remove your tyres to replace the batteries …
It is also worth noting that any the car mounted systems cost significantly more to implement than the hand held methods.
You can even combine both external and internal IR readings if you are brave (and rich!)
Here is a video that US distributor has done. He has combined an installation of both internal and external IR tyre temperatures sensors and made this video:
I thought it was fascinating and having the tyre pressures are live too is an added bonus.
If you’ve not seen anything like that before I hope enjoyed watching it. I also hope you can see where I am coming from in terms of potential data overload … 🙂
It Is Your Choice (… But Choose One)
Know you now the options for measuring racing car tyre temperatures, you just need to make a choice for yourself about which approach is best for you at your stage.
If you measure racing car tyre temperatures they can offer you a key insight into how your racing car is working.
Even if you just take handheld measurements in the pits, that is much better than doing nothing, even with the practical drawbacks.
Good luck 🙂
Enjoyed this? Check out these other articles:
If the temperature of your racing car tyres are out, you’ll be left wresting a bear. Avoid that & gain control of your cars grip levels in this detailed guide: https://www.yourdatadriven.com/what-should-the-temperature-of-your-racing-car-tyres-be/
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/