tire temperature gauge

[T77911S]

can you use a pyrometer on street tires to determine correct pressure.

do you have to use one specifically for tires (one that probes the tire) or can you use an infrared temp sensor

what about nitrogen in street tires
I had the 930 at the track last month and my tire temps were 5 to 10 degrees higher coming off the track.

should I just chalk the tires next time. but then they will be under inflated until they heat up.

[naparsei]

IR is tough because surface of tire cools quickly. Pyrometer is better.

Focus less on a number, and more on the delta across the width of the tire.


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[dw1]

Originally Posted by naparsei

IR is tough because surface of tire cools quickly. Pyrometer is better.

I don't understand this because an optical (IR) pyrometer is a type of device, not two different ones.

To answer the original question, yes an optical pyrometer is very worthwhile tool for measuring tyre temperatures, and for heater & A/C troubleshooting.

There are a few watch-outs, however. Look at the specs for spot size variation with distance and response time. Also, the really cheap ones aren't all that accurate, but may be acceptable for your needs.

Btw, I use quite a variety of contact and non-contact temperature probes in my work, including body temperature ranges, HVAC temperatures, injection molding temperatures, and metal processing temperatures. The best medium-priced non-contact, small area temperature measuring device I've used are the Fluke 568.

[gremlin]

Originally Posted by dw1

I don't understand this because an optical (IR) pyrometer is a type of device, not two different ones.

The reason that you don't use an optical Pyro on a tyre is that you're measuring the surface temp and that cools extremely correctly. A needle type pyro is inserted below the surface into the tread depth where the temperature is more stable and easier to measure, but even that drops off correctly.

When we're measuring temps for a track car we generally get some hard laps in and bring it straight into hot pits to do a measurement right away without it sitting or the driver getting out. Even driving into the cold pits will drop it significantly.

While it can be used on street tyres I'd say just run the manufacturers recommend pressures for the tyres, as it'd be hard to get yourself into a situation where the measurements would work and be consistent.

[T77911S]

yes, looking for temps across the width,

I have a fluke infrared one now. did not think about taking it with me. I also never expected tire temps to go up as much as they did. I also did not expect street tires to get that hot and "sticky".

I saw a probe one for just over 100.

[Quicksilver]

There is a little good info here and more bad info here.

You could use an IR thermometer but you would get information of limited accuracy and even of less use. In the length of time and distance it takes to pull to a stop and measure the 4 tires, the numbers will have skewed enough to be more likely to mislead than to inform.
I have seen IR used to read tire temps in real time but that was a very complicated system with 3 sensors mounted in each wheel well. It recorded the inner, mid, and outer temperatures continuously as the tires heated and cooled out on the track. It produced extremely relevant data that was very interesting. One thing it showed was how rolling across the cool asphalt pretty much instantly cooled the tires surface.
- The important detail is that almost all of the tire heat is generated inside the carcass of the tire from the repeated bending and flexing of the rubber. Outside heating is from slipping the tire which is only significantly generated when the driver makes mistakes and isn't that relevant.

To get really usable data the temp needs to be taken from under the surface where it is generated to begin with and it changes at a slower rate because rubber is an insulator. You still need to get the temperatures as quickly as possible and I would recommend that you do the tires in the same order. (After getting a baseline for how fast the temperatures fall off and correct for that.)

BUT. . .
This doesn't make a difference for what was asked in the original post.

- Tire temps are used in conjunction with alignment adjustments to setup a car's suspension. The temperatures mean WAY more about alignment then tire pressure. (You will ignore some level of 'inner/middle/outer' inequality of temperature to get the suspension right.)
- Skid pad times and handling on the pad is a MUCH more valid and productive way to adjust pressures for cornering performance.
- Temperatures on the street have WAY more to do with alignment than pressure. Same with tire wear. During the normal straight line and light to medium cornering it is going to heat the inside of the tires because of camber.

So what are you trying to achieve? Comfort? Long life? Handling? Safety? A compromise between them?
- Comfort is the easiest. (Run the pressures a bit on the low side and use a tire with more sidewall.)
- Long life can be best achieved by closely measuring tire wear and adjusting for it.
- Handling is achieved by skid pad and track testing along with step by step adjustments. (Along with taking lots of notes.)
- Safety mostly involves running high pressures which gives improved tread block stability in the dry and a major improvement in grip in the wet.

---------------------------------------
There is a bunch involved with this. So you need to define exactly what you realistically want and how much time are you willing to devote to it.

[Ayles]

Ahh my old pit crew job circa 1992. Needle pyrometer. Measured outside, middle and inner.

[1979-930]

I use the pyrometer to check temps side to side. Depending on track layout and direction I’ll run a 1/2 to 1 lb more pressure in the inside tires so they are closer to even press & temp when hot.
They are never perfect temp wise but closer than when not checking and adjusting.


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[T77911S]

trying to figure out optimal tire pressure for track.

first track day in the 930.
tire pressure hot was in the mid to upper 40's at first.
I kept dropping pressure but since it was my first time on the track I was getting use to all the turn in oversteer and how the car handled.
the car "seemed" to get better as dropped the pressure but not sure if it was my driving, the fact that I had slowed due to brake fade or if it was tire pressure.

at first I really over drove the tires/car as I wanted to learn what the car did beyond its limits so I did spend a good bit of time sideways. (no spins although there were a few times I submitted to the fact I was going around but did not).

would love to have access to a skid pad but not one around that I know of.

so I want to take tire pressure out of the handling/my driving equation.

thinking about going up to 20/27 T bars. should reduce over steer just a little and stiffen up without being to bad on the street.

[porsche930dude]

there are aftermarket tpms systems that monitor pressure aswell as temperature