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August 13th, 2019 Posted by: Chris

 

 

Dear Tire Guy,

I am new to the PCA and attended my first DE last year. I loved it and plan on attending all of the DE’s this year. I am excited about improving my driving skills and want to learn as much as possible. I did a lot of listening at the DE and heard several different people talking about adjusting their tire pressures. Is this something I should worry about?

Anonymous & Slow

 

Dear Anonymous & Slow,

You have asked a great question and one that I get a lot. The easy answer to your question is “Yes”. The pressure in your tires is one of the most important aspects of setting up your car for track driving. Tires are the reason cars stick to the road and if you look at pictures of how little rubber is actually touching the ground, the “Contact Patch”, it might scare you. By paying attention to tire pressure you can change the size and effectiveness of the contact patch.

 

For performance drivers wanting to milk every last bit of traction out of their tires this is especially important. The amount of pressure in a tire also affects the way the car handles and can change the amount of over-steer/under-steer inherent in the vehicle. Unfortunately there is no magic formula for deciding what tire pressure will give you the best contact patch while you are on the track. You will undoubtedly hear the terms “Cold Pressure”, the pressure you set your tires at to start a track session and “Hot Pressure”, the tire pressure at the end of a track session. Your ideal tire pressure is the number that gives you the largest Contact Patch. Start your Cold Pressure too close to your ideal pressure and you will be fast in the beginning of your session and over inflated and slow at the end. Start the Cold Pressure too low and you risk never reaching your ideal pressure which means you will be slow and loose the whole session. There are a whole host of factors that contribute to determining how much your tire pressure will increase over a period of time: size of your tires, vehicle type, make and model of tire, compound, air vs. nitrogen filled, aggressiveness of the driver, daytime temps, type of track. All of these factors and more play a role in how much heat is imputed into your tires and thus how much the pressure will rise. Finding your ideal tire pressure for a particular track typically involves: setting the cold pressure based on past experiences, taking tire temps, hot pressure readings, then making small adjustments based on this data and feedback from the driver. This can take just a session or two when working with a driver that has lots of historical data to a whole weekend for someone just starting out. Now to complete the answer your question, Yes, however at your stage in the game you will be just fine maintaining the tire pressures as specified by the vehicle manufacturer. As you move through the next couple of DE’s and start to feel more comfortable at higher speeds and can carry this speed smoothly through the turns then it may be time to start manipulating the tire pressure 1 or 2 psi. Larger adjustments will come when you move up into higher run groups within the DE structure and as you move to more track orientated tire selections.

Thank you for your question Anonymous & Slow, undoubtedly lots of other beginners were wondering the same thing. Until next month, Drive on!

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