#TRTECH: How To Properly Set Your Tire Pressure

Rupert Crook is our race steward for the 2019 Giti-Formula V1 Challenge, he’s in charge of reviewing race incidents, settling disputes, and making sure all drivers compete within the rules. That’s because he’s quite the expert himself!

It doesn’t get any more British than this

With over 30 years of racing and instructing experience, Rupert is ideally qualified to discuss all matters relating to fast cars. He has raced single seaters, saloon cars, GT cars and even Group C Le Mans cars. He’s worked with many manufacturers was a Performance Driving Instructor with Aston Martin for over 10 years, traveling and teaching all over the world.

He’s settled down and been living in the Philippines for the past five years though, and he’s eager to share his expertise with you in our #TRTECH series. Information for someone who wants to reach the next level with their car and maybe even head to track for the first time!

Let’s start off with one of the basics for a trackday: setting the proper tire pressure.

“The tyre pressures you run on a race track will have a massive impact on your car’s handling and on its tire wear, so it’s worth spending some time getting this right.”

Repping Aston Martin at CIS

Let’s assume you are using your car’s standard road tires and taking your car onto a track for the first time. In case you are wondering, with normal road driving you should run your tires at the manufacturer’s recommended pressures–they have spent millions of dollars in conjunction with tire manufacturers, to provide you with a tire that operates in all circumstances and additionally gives you a long and trouble free life.

But you are about to push this to the limit, and beyond!

As you drive around a track, at greater speed than you would normally be doing, your tyres will get warm, the air inside them expands–and consequently your tire pressures will rise. The hotter the tire, the greater the pressure. The trick is to find the best tyre pressure–for your car–on each particular track.

1. Start with a lower pressure

I recommend starting 3psi lower than the manufacturer’s recommended pressure on a cold tire before you set off out onto the track. Build your speed for a couple of laps and then come into the pits. Check each tire’s pressure as quickly as possible and write each one down–ideally you are aiming for a pressure around 5psi above the road recommendation.

A tire pressure gauge can easily be bought online

2. Check for sidewall scuffing

Pitting in is also a good time to see how the tread of the tyre is scuffed. If the sidewall is becoming scuffed increase the tire pressure as you need to make the tire stiffer. On the other hand if only the centre of the tire is scuffed–and it doesn’t cover the whole tread–reduce the tire pressure. You are aiming for an even scuff or wear across the whole tyre.

In this case, the wear is still safely on the tread portion!

3. The feeling of Under/Overinflating

You will very quickly notice if your tires are under or overinflated as the car will feel dramatically unstable. An overinflated tire reduces the contact patch between the tire and the tarmac–bear in mind that this is only about the size of your hand! 

The result is worse traction, less grip and reduced braking performance, which is magnified in the wet. A similar feeling is created by an underinflated tyre. The car will feel unstable and grip levels and braking distances will be affected.

It took three tries until we found the proper setting for this session, the driver constantly felt that grip was lacking and adjusted accordingly!

4. Different tire pressures front and rear?

Different car manufacturers would recommend different tire pressures on the front and on the rear of your car. Why? Front tire pressures are commonly higher than the rears, to compensate for the extra weight of the engine and transmission–especially in front wheel drive cars.

An obvious exception to this are BMW or other rear wheel drive cars. Always check the manufacturer’s recommendations–usually on a sticker inside the driver’s door, or in the handbook.

5. Don’t be afraid to ask!

Trackday people are usually very friendly and helpful. If you see someone with the same car as you, who looks to know what they are doing, and is going pretty well go and have a chat. Ask what pressures he is running–it may just point you in the right direction!

And a fun story about using the wrong tire pressure on purpose…

You probably shouldn’t try this!

Heavier cars will run a higher pressure than lightweight cars but I recall putting the front tire pressure up to 60psi on a racing Mini many years ago–for one flying lap it was superb and usually guaranteed a pole position!

A very light car, on extremely small wheels, the idea was an experiment to make the car “float” in the corners. Very little braking was required–rather we flung the car sideways into a corner, thus scrubbing off speed, and could power the car through the corner, thus carrying superb exit speed. Yes, for sure it murdered the tires but the way it danced around the track was really great fun and it looked pretty spectacular!

However the downside was that the tires wore ridiculously quickly and were virtually unusable after one lap. So only to set a qualifying time!

And remember, probably the biggest adjustment you can make to improve tire wear is, you, the driver. Avoid sliding the tires, especially in the corners, avoid locking up the wheels under braking, and drive as smoothly as possible. It will pay you in lap times, overall speed and in sheer satisfaction!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s