Harbor Frieght Infrared Thermometer & tire temps.: Grassroots Motorsports forum: Grassroots Motorsports Magazine

Subscribe get a full year for only $23.95 Sample Free Test Drive—no strings attached

April 22, 2010 6:44 p.m. RedS13Coupe Reader

I have heard all about how and why probe types are better for tire temp use, but I am wondering how bad off I would be to ignore it?

I am looking to use it with out schools Formula Hybrid team. We have a small open wheel car we will be testing in our parking lot, and I am thinking with out having a long pit lane (or any for that matter) to come down cooling of the tire surface will be less of an issue.

Our budget certainly likes this option more then a probe type too.

Considering we don't have money to throw around, we can get to the car very quickly after it drops from race speed, and the IR would be more convent for getting a number of other temperatures is this a bad idea?

Are the HF ones going to be much worse then other options of a similar price? We are looking to test again on sunday and it would be nice if I could just go pick one up before then, but if a much better option required shipping we skip that data this weekend.
April 22, 2010 7:00 p.m. Dr. Hess SuperDork

The HF ones won't be any worse than anything similar. Remember that it's the relative temps across the tires that are important, and if the whole thing is off 5 degrees, big deal, as long as it's off 5 degrees the same way on all 3 temps (inside, center, outside). I use a HF IR digital pyrometer. It's real handy and great for messing with the cat.
April 22, 2010 7:10 p.m. Jensenman SuperDork

A while back I compared my HF infrared to my Longacre memory pyrometer. Same car, same day, used one right behind the other, even flipped the order of use. The HF showed somewhat lower temps (average of about 8 degrees F lower) but like Hess said the relative temps were the same.

Now that I have had time to consider it, the HF (or any other surface temp reading unit) might present a problem on a cold day since the surface of the tire will cool very quickly compared to the inside of the rubber. That could possibly skew the relative readings.
April 22, 2010 7:11 p.m. kb58 Reader

The trouble is that it's only measuring the surface temperature. The temperature slightly below the surface is the true temp, since the outer surface has time to cool off between the last turn and when they're measured.
April 23, 2010 5:47 a.m. foxtrapper SuperDork

A probe is better because it gives a very localized temperature reading. It records what the probe tip sees.

A hand held scanner averages the reading over a much larger area. At least I think it does. It might also record the highest single peak value it sees in that scanned area. Either way, it will not be as precise as a probe.

Which means when trying to study tread block temperatures across a tire face, the probe is more accurate. Provided that you do the readings instantly, and factor in the heat from the engine, and the shrouding from the fenders, and the time differential from the readings.

For most of what you want, a hand held scanner will work adequately, if held close to the tire. It's also darn handy to have for other things, like looking at exhaust temperatures in header pipes, or radiator temperatures.

Course, a probe can be made for $1. Buy a thermister from RadioShack, solder some wires to it, shove it in the end of an old ball point pen. Wala, a temperature probe that your handy dandy multimeter reads.
April 23, 2010 7:07 a.m. Woody SuperDork

foxtrapper wrote:

Course, a probe can be made for $1. Buy a thermister from RadioShack, solder some wires to it, shove it in the end of an old ball point pen. Wala, a temperature probe that your handy dandy multimeter reads.

There's your Tech Tip right there.
April 23, 2010 8:06 a.m. Brotus7 New Reader

Or get this.

http://cgi.ebay.com/2-K-Type-Digital-Thermometer-Thermocouple-Sensors-/25061967625... And http://cgi.ebay.com/K-Type-Thermocouple-Probe-Digital-Thermometer-300-C-/150425105...
April 23, 2010 8:48 a.m. klipless Reader

The probe is the way to go. It'll give you a true reading of how hard the tread blocks are working, and will give you the best chance to nail the inflation and camber settings. That said, they're not cheap.

If you're going to use the IR gun, then measure the tire that was under the hardest load most recently first, then work your way around. Take a second measurement of that tire once you have the other four. Comparing the two reading of that tire will give you an idea of what kind of accuracy you're missing due to tire cooling. Actually you should be doing that with a tire probe too.
April 23, 2010 9:38 a.m. pigeon HalfDork

I wonder how my kitchen probe thermometer would work in this application? Seems to do just fine with chicken on the grill but can take a few seconds to get a stable reading.
April 23, 2010 10:25 a.m. Dr. Hess SuperDork

If you want to use a probe, then why not try: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95382 which is a whopping six bucks, less your 20% off coupon, of course. Reads from -4 to +392F. That should do it, I'd think.
April 23, 2010 11:41 a.m. foxtrapper SuperDork

In reply to pigeon:

Kitchen probe should work just fine.
April 24, 2010 2:00 a.m. RedS13Coupe Reader

klipless wrote:

The probe is the way to go. It'll give you a true reading of how hard the tread blocks are working, and will give you the best chance to nail the inflation and camber settings. That said, they're not cheap.

If you're going to use the IR gun, then measure the tire that was under the hardest load most recently first, then work your way around. Take a second measurement of that tire once you have the other four. Comparing the two reading of that tire will give you an idea of what kind of accuracy you're missing due to tire cooling. Actually you should be doing that with a tire probe too.

That is a good tip about going back and taking temps a second time... Will do.

Went and got a harbor freight one today. $24, but printed the 20% coupon for a total of about $16 and a free flashlight... Not bad.

Doesn't seem too bad, with in a couple degrees for sure. Also has a setting to hold max, hold min or lock a temp on screen. Definitely varies with distance, but it seems like we can pretty much put it against the tire to avoid measuring a large area and losing temp over distance.