Tire Temps
03-01-2006, 03:09 PM
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Tire Temps
There are several ways to alter handling balance. You can change spring rates, bar rates, cross-weights, suspension geometry, shock rates, roll center location, tire pressure, or static weight distribution. All of these are used to get better tire traction. The best measure of tire traction is temperature. Tire pyrometers are cheap, easy to use, and the single most important tool you can own to get a car setup dialed-in.
Measuring Tire Temps:
- Always record temps, even if the car is out only for one or two laps
- Take temps after the event when possible
- Record pressures (cold and hot) as well as temperatures
- Use a tire temp chart (you can make your own)
- Take temps at 3 spots on each tire about 1 inch from each edge and in the middle
- Always take temps in the same lateral spot on the tire tread
- Always take temps in the same order on the tire (either inside or outside first, than middle)
- Always start at the same tire
- Always go around the car in the same direction
- Move fast
- While fast is important, make sure that each reading has stabilized before moving on.
- Unless you use a memmory pyrometer, have someone record temps while the other takes the temps
- The 4th tire in the sequence will lose heat by the time the temps are taken. After measuring the 4th tire, check the first tire again so you can see how much the temps have dropped. This will give you an idea how hot the last tire was when you pulled in.
- Take tire pressures right after taking the temps, go in the same order (hot and cold).
- Once in a while, check the tire pressures after 5 to 10 min. If your pressure is higher than when you pulled in, you have excessive heat coming from your brakes.
- The needle on the probe should be inserted into the tire tread.
- Keep heat in the probe by holding your finger over the needle while taking the temps.
- Slide the probe over the tire tread surface when moving the probe across the tire to keep the probe hot.
- Taking tire temps at different locations around a track will give you more information about that section of the track and how the tire traction is.
- The driver should avoid hard braking coming into the pit.
- The drive should not take a cooldown lap. The tires will cool too quickly, giving a false reading.
Once you have the information:
- Average the temps of each tire
- Average the temps on the left side
- Average the temps on the right side
- Average the temps on the front
- Average the temps on the rear
- Average the cross temps (RF/LR and LF/RR)
Now you should know how to take tire temps. Use the data to make changes on your car to see if you can get more traction (better handling). Just remember to make ONE change at a time!!!!
If you can get each tire working the same you will be faster!
Measuring Tire Temps:
- Always record temps, even if the car is out only for one or two laps
- Take temps after the event when possible
- Record pressures (cold and hot) as well as temperatures
- Use a tire temp chart (you can make your own)
- Take temps at 3 spots on each tire about 1 inch from each edge and in the middle
- Always take temps in the same lateral spot on the tire tread
- Always take temps in the same order on the tire (either inside or outside first, than middle)
- Always start at the same tire
- Always go around the car in the same direction
- Move fast
- While fast is important, make sure that each reading has stabilized before moving on.
- Unless you use a memmory pyrometer, have someone record temps while the other takes the temps
- The 4th tire in the sequence will lose heat by the time the temps are taken. After measuring the 4th tire, check the first tire again so you can see how much the temps have dropped. This will give you an idea how hot the last tire was when you pulled in.
- Take tire pressures right after taking the temps, go in the same order (hot and cold).
- Once in a while, check the tire pressures after 5 to 10 min. If your pressure is higher than when you pulled in, you have excessive heat coming from your brakes.
- The needle on the probe should be inserted into the tire tread.
- Keep heat in the probe by holding your finger over the needle while taking the temps.
- Slide the probe over the tire tread surface when moving the probe across the tire to keep the probe hot.
- Taking tire temps at different locations around a track will give you more information about that section of the track and how the tire traction is.
- The driver should avoid hard braking coming into the pit.
- The drive should not take a cooldown lap. The tires will cool too quickly, giving a false reading.
Once you have the information:
- Average the temps of each tire
- Average the temps on the left side
- Average the temps on the right side
- Average the temps on the front
- Average the temps on the rear
- Average the cross temps (RF/LR and LF/RR)
Now you should know how to take tire temps. Use the data to make changes on your car to see if you can get more traction (better handling). Just remember to make ONE change at a time!!!!
If you can get each tire working the same you will be faster!
03-01-2006, 05:05 PM
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Thanks.
I got most of this information out of the High-Performance Handling Handbook by Don Alexander. If you don't have this book - get it before you make any handling upgrade. Great info on what different mod's will do to your handling and how to maximize the performance.
I got most of this information out of the High-Performance Handling Handbook by Don Alexander. If you don't have this book - get it before you make any handling upgrade. Great info on what different mod's will do to your handling and how to maximize the performance.
03-02-2006, 03:02 AM
#6
Originally Posted by sean1967
if you are really **** about it, you can use nitrogen (gaseous) to limit the temp change
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03-02-2006, 10:04 AM
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I am a little rusty, but here is what I remember.
It also comes from the ideal gas law:
PV=nRT
Since we assume that V is constant and R is a constant. Than
Pressure will be relative to nT. Since humid air n > dry air n. Than less temperature gain will cause a higher pressure.
One would assume that since humid air has a much higher heat capacity than dry air, the temperature gain would be less. Yet, the temperature gain is coming from the tires, not from the air inside the tires.
It also comes from the ideal gas law:
PV=nRT
Since we assume that V is constant and R is a constant. Than
Pressure will be relative to nT. Since humid air n > dry air n. Than less temperature gain will cause a higher pressure.
One would assume that since humid air has a much higher heat capacity than dry air, the temperature gain would be less. Yet, the temperature gain is coming from the tires, not from the air inside the tires.
03-03-2006, 05:20 AM
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Originally Posted by MoodDude
I am a little rusty, but here is what I remember.
It also comes from the ideal gas law:
PV=nRT
Since we assume that V is constant and R is a constant. Than
Pressure will be relative to nT. Since humid air n > dry air n. Than less temperature gain will cause a higher pressure.
One would assume that since humid air has a much higher heat capacity than dry air, the temperature gain would be less. Yet, the temperature gain is coming from the tires, not from the air inside the tires.
It also comes from the ideal gas law:
PV=nRT
Since we assume that V is constant and R is a constant. Than
Pressure will be relative to nT. Since humid air n > dry air n. Than less temperature gain will cause a higher pressure.
One would assume that since humid air has a much higher heat capacity than dry air, the temperature gain would be less. Yet, the temperature gain is coming from the tires, not from the air inside the tires.
It might have something to do beyond 'ideal gases'...when you compress air (which has moisture) very quickly, the temp increases b/c moleculses are bonding (an exothermic reaction) & the opposite occurs when you decrease the pressure. I'm thinking that Nitrogen might not be as prone to bond under the type of pressures it will experience in car tires.
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