Welcome to the SPS/Solotime Product Information and Support Site Minimize

You are at the SPS/Solotime Product Information and Support Website.

If you would like to purchase any of our extensive line of products and graphics for the autocrosser, track day enthusiast or amateur racer, please visit our main website at www.solotime.com or www.soloperformance,com.

This Product support website is designed to provide answers to common questions, help with problems and a repository for product manuals and information.

 
  

Articles Minimize
Last Updated 12/28/2007 5:10:23 PM


Pyrometer Tips

Pyrometer Tips
Table of Contents
A. Proper Depth and Location
In order to get consistent and relative tire temperature readings you must be sure to insert the probe as near to the cord as possible. You must also insert the probe to the same depth at all locations at each and every tire. Temperatures should be taken at 3 locations on each tire. Take one reading at the outside approximately 1.5" from the edge, one reading in the middle, and one reading approximately 1.5" from the inside edge. Do every tire the same way at the same depth and location.
As you insert the probe deeper into the tire you will find more heat. If you insert the probe half way in at one location and then all the way in at another location you will get temperature differences due to the different depths. You are trying to see relative numbers based on how the tire is heating due to camber or loading changes. Improper depth can confuse the true issue.
By inserting the probe to a depth down near the cord you will also use the surface rubber to momentarily insulate outside elements such as brake and engine heat away from your true temperatures. Further, by getting down near the cord you will also measure heating that is caused by an elastic stretching of the rubber. If your probe is too shallow you will not see the heat generated by the pulling of rubber from the tire carcass.
Another thing to consider when using a probe type pyrometer is that rubber is a poor conductor of heat. The metal probe will suck the heat out of an insertion hole very quickly as the metal probe transfers heat quicker than the rubber. At the first tire in a temperature session you should pre-heat the probe by inserting it in the rubber a few times before taking your readings. Once the probe is pre-heated you will get faster, more accurate and relative results.
Be careful not to leave the probe inserted too long in any one location. You need to measure the temperature rise at its maximum point and no more. If you wait too long the insertion point will start to cool, giving you inaccurate readings.
Pyrometers with an anticipation feature speed up the temperature taking process and automate the procedure so that your readings are taken as quickly as possible. You simply insert the probe and immediately hit the read button. The pyrometer will calculate the rate of temperature rise and automatically lock in the highest reading. The pyrometer will then prompt you to move to the next location. Pyrometers with anticipation complete all 12 temperatures in nearly half the time of conventional pyrometers.
Top  
B. Adjustable Tip Probes
If you use a pyrometer with an adjustable tip probe you can set the probe to match the rubber gauge (thickness) for the different tracks that you run. The adjustable tip allows you to bury the needle of the probe all the way to the housing to insure that you are at the same depth each time. Repeatability increases dramatically and the relativity is better because you are always down near the cord with your probe tip.
Top  
C. Getting to the Tires Quickly
You should always get to your car as quickly as possible to take tire temperatures. Each time the tires roll across the pavement the cooler pavement is sucking heat from the tires, which can skew your readings. You should even have your car stop at the nearest safe place to the track and have a crewmember waiting to take the readings.
Top  
D. Camber Adjustments
Your pyrometer is a tool to see if you need to make a camber adjustment. 
Top
E. Taking Advantage of New Tires
New tires are a big investment. Whenever a new set goes on the car I put more value in the tire temperatures from the sticker tire run and make sure that I get good temperature readings. When the tires are new they will have more friction and generate more heat than at any other time. The additional heat and added friction can provide subtle clues that may not be seen with worn tires.
Further, new tires are not worn down on any part of the contact patch. Therefore, your readings are not skewed by an area on the tire that has already been ground off. New tires have more friction so the tires are less likely to slide or spin. The temperatures more closely reflect the heat generated by tire loading. Looking at the effect tire loading gives you an indication of what the car will do in the future. Hopefully the car is already fast for the main event, but the new tire temperature opportunity might guide you into adding a touch of bite or putting in more stagger based on what you learn from your readings.
Be prepared and insure that you get a good temperature reading when new tires go on the car.
Top
F. IR Versus Probe
Probe type pyrometers are better for use on tires if used properly. Infrared type pyrometers measure only the tire surface and do not get inside the rubber to find the true results. The rubber down at the cord is insulated away from the outside elements providing for more accurate readings. Rubber at the cord is also heated due to elastic stretching of the rubber. Probes can reach in and see this heat.
Infrared pyrometers measure only the surface. The surface will be cooler as heat is dissipated off the surface very quickly due to the outside air cooling and simply rolling across the cooler track temperature. Typically the surface temperature is 20-40 degrees cooler than temperatures taken with a probe. Infrared temperatures will also be affected by artificial brake heat and engine heat.
You can use the infrared pyrometer for tire temperatures but it is a compromise. Your camber temperature curves will not be shown with as much clarity. Temperature differentials will be more dramatic with a probe allowing you to be more precise in your camber adjustments.
Infrared pyrometers do work well for surface temperatures such as track temperature, cockpit temps, header temps, brake temps, and the like. Probe type pyrometers do not work well for surface temperatures.
Top
G. Summary
Used properly tire temperatures will allow you to see what the racecar is going to do on a long run as the tires heat and wear. You will be able to see through what might be covered up by the extra grip from your new tires as racecars always feel better when the tires are fresh.
You can learn to anticipate what the car is going to do on long runs by using temperature averaging as a tool. Temperature averaging is of little benefit if the balance of the car is dramatically off. Remember your readings have more meaning as the car approaches optimum handling. Temperature averaging is of most benefit when your car is already very fast and you are looking for that final edge.
Top  
Partially adapted from article written by Jeff Butcher, Longacre Racing Products