How To Use Tyre Temperatures in Car Maintenance

We are all familiar with maintaining our tyre pressures and checking the tread depth as a safety and fuel mileage necessity, however things like damaged or worn out suspension components or an out of alignment cindition can be just as devastating.

Usually though worn suspension components or alignment  problems may not be noticed until the tyre has been damaged to a point of being unsafe. this of course also costs money to not only repair the worn components or perform an alignment but the tyres will usually have to be replaced prematurely as well.

Here is a nice little procedure that can catch these problems early by learning to understand the process of reading tyre temperatures. This can seem a little perilous to the inexperienced, but with the help of this information hopefully you will soon be able to use tyre temperature as a very useful tool to determine:

  • Best tyre pressure
  • Best camber settings
  • If you are overheating tyres
  • Tuning the Chassis for those track days

The only trick to understanding tyre temperatures is to realize that if one section of the tyre is “working” harder than the other ones, its temperature will be higher.

Traditionally, tyre temperatures are measured at the inside edge, middle, and outside edge of the tyre.

It is critical to take temperature readings as soon as the car comes off a long drive or the track otherwise the temperature across the surface of the tyre will become more uniform as the whole tread surface cools.

A sample sheet of how to record your tyre temperatures is shown below:

All of the temperatures are recorded as if you were looking down on the top of the car.  Logically, the right front tyre is on the right front of the sheet and the outside temperature of the front right tyre is recorded on the outside.  Following this pattern is important otherwise interpreting different sets of tyre temperatures can become impossible.

Now to make sense of the temperatures in terms of component wear, alignment or suspension tuning,

Optimizing tyre pressures

Since we know that the hardest working portion of the tyre will be the hottest, if the tyre temperatures show that the middle of the tyre is significantly hotter than the outside portions of the tread (a temperature variation of more than 10-15 degrees) the tyre is over inflated.  Too much pressure causes the center of the tyre to bulge, resulting on most of contact patch being in the center of the tyre.  If you see temperatures like this, reducing tire pressure should normalize the temperature across the tread width.

CAUTION: Never adjust tyre pressure on warm or hot tyres. Wait till they cool first!

Optimizing camber

Using the same assumptions about tyre work and temperature relationships, we can learn about camber settings.  If the outside of a tyre is the hottest portion, it means that the car does not have enough negative camber.  The lack of (negative) camber means that in turns the car is riding on the outside of the tyre causing it to work the hardest.  To correct this, have your mechanic perform a proper alignment or simply dial in more static negative camber.  The result will be more evenly distributed tyre temperatures. This simple change can fix a car that won’t push through turns, and more than likely will provide – quicker lap times.

Overheating the tires

This is fairly straightforward; the tyre temperature will let you know if you are overheating your tyres.  While this is fairly intuitive, most people don’t check tyre temperatures.  For as little as £9.20 it costs for a pyrometer, there is no reason not to ensure you aren’t going to kill a brand new set of tyres in just a few miles.

Tuning the chassis

Tyre temperatures can be a very useful tool in determining flaws in the suspension set up a vehicle.  For instance say a car is running too hot on the front left tyre (front wheel drive car).  Not only will the tyre not survive, but if there is not another tyre compound available, the suspension tune must be changed to compensate.

On this front wheel drive car, if the left tyre is that hot, chances are that the driver is spinning that tyre exiting turns.

Modulating the throttle is one way to correct this problem although, an under steering chassis will push the car through the turn allowing the tyre to spin.  By changing spring rates or roll stiffness (sway bars) a little more over steer can be dialed in, letting the car rotate better in turns and saving the left front tyre.

Of course tyre temperatures are not the end all be all of suspension analysis, but because pyrometers can be had for fairly cheap it is a good way for people just getting into tuning their suspensions to get their feet wet and set their car up to handle better all at the same time.

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