jford

Wanting to get a pyrometer to try to dial in tire pressures more effectively. I was looking at a laser pyrometer from Longacre for about $80. Anyone have any expereince with this unit? Is the probe kind better or worse than the laser version?

I do want an inexpensive model but not at the cost of accurecy and usablity...how's that for stating the obvious.....lol. Thanks.

Jamie

jerome951

Probe-types should be more accurate as they read below the surface of the tread, which can cool more quickly when exiting the track.

If you are interested in a non-contact IR type, the one sold by Harbor Freight for $50 appears to be the same as the Longacre (rebadged Accutech). I just picked one up for other diagnostic uses as well as tire temps.

kurt M

One tire saved will pay for a good probe type. Get one with memory for ease of use. Just go point to point and after you gather all data quickly you can sit back and plan any pressure moves or susp ajustments.

ltc

I have the Longacre 50640 probe type digital pyrometer:
http://www.longacreracing.com/catalo...id=875&catid=7
which I use on my son's kart.

I have been very happy with it so far. Nice case, easy to use, good battery life.

Here is Longacre's take on probe vs. infrared (non contact):
http://www.longacreracing.com/articles/art.asp?artid=9

Here is Longacre's Pyrometer tips:
http://www.longacreracing.com/articles/art.asp?artid=16

RedlineMan

Jamie;

Probe type is the ONLY type for tires, and make sure the probe is at least 3/8 long. The non contact type are good for your pot roast, Thanksgiving turkey... or brake rotors.

Kurt is right; memory is really nice. If you ever try to do temps with a piece of paper and a pen, by yourself, at Sebring (meaning WINDY), you'll understand.

Joe Weinstein

does anyone make a pyrometer with three probes, that will do inner, middle, and outer
at one time? That would be cool. Of course it would have to allow adjustment for
different-width tires. We'd like it to remember four tests at least, too.
Joe

Cory M

I also recommend that you go with a probe rather than the laser style, it allows you to go below the surface of the tire and obtain a more accurate reading. Hoosier specifically recommends against using laser pyrometers in their tire literature (available on their website). Although the accuracy may not be super critical if you are more concerned with tuning your pressures and suspension settings based on the relative difference in temp across the tire tread, but you could probably pick up some heat radiating from the engine and exhaust on the inside rear temp reading.

ltc

This is very close to what you want:

http://www.longacreracing.com/catalo...id=188&catid=7

It has a single probe, but it will record and display all 12 temp measurements; 3 per tire: outside, middle, inside.
Making 3 measurements/tire with a single probe is very quick.

It will record 10 sets of readings (120 individual temps, 30 per tire). You can print directly:
http://www.longacreracing.com/catalo...id=192&catid=7
or download to your laptop/PC.

$800 for the pyrometer and printer + laptop.

ColorChange

LTC, that is the pyrometer computer I have. Not only does it store all positions, it has a predictive mode that allows taking super fast temps before waiting for the probe to reach final temps.

jford

Great feedback! Probe it will be and with memory. Really makes sense to go with the better unit as it is a one time buy vs. thousands of dollars potentialy spent on tires in the coming years.

This is precisly why I asked this question of this board, thanks again.

Jamie

ltc

ColorChange,
A $400 pyrometer and you still think you won't end up with a tow vehicle and trailer?

I have my hands full with tire pressure and lug nut torque; a pyrometer would only add to my confusion.

ltc

Jamie,
If you're getting the memory pyrometer, you may want to consider this, to make a matching set:
http://www.longacreracing.com/catalo...id=210&catid=8
4 tire hot/cold temp memory digital tire pressure gauge.
Yes, I have one, but again, it's for my son's karting. Found it on eBay a year or so ago.

ColorChange, if I were a betting man, I'd guess you already have one of these.

jford

Lewis,
Thanks for the links, very helpful indeed.

Jamie

Darren

I have that $400 one also, its super sweet because you can take all of the readings within about a minute. I've compared the readings to the infrared and there is always a difference in the readings. The difference (in my experience) is relative though, and with tire temps you really mostly care about the relative readings across the tire. In other words, my infrared consistantly reads numerically lower temps on the tire, but it can identify which part of the tire is hotter/colder.

So I think the infrared would work, but it takes entirely too long to take and write down all of the readings, which greatly decreases your accuracy.

RedlineMan

Here's the technical explanation of why you NEED a probe:

1) The surface of a tire cools quickly, and unevenly on a sedan.
2) The suface of the tire is not in jeopardy, and is NOT the failure point.

1) Since it is very difficult to get temps immediately after a hard run, the tire will be cooling to some degree as you cycle into the pits, even if you come in on a hot lap. In a sedan, the tires are shielded by the fender wells, and as such the outer portion of the tire will tend to cool more since it is more exposed to some amount of airflow. This "can" distort the accuracy of your readings somewhat.

2) The heat a tire generates is largely coming from mechanical fluxure of the carcass, not surface friction. In other words, it is coming from inside, not outside. This heat therefore radiates from inside, under the tread surface, and the area between the cap ply (tread) and reinforcement ply (first layer of chords) is the critical juncture. When you "blister" or "chunk" a tire, this is where it separates.

To access this area, you would obviously have more luck with a probe type pyrometer. An IR pyrometer CANNOT read this area, and so is "relatively" worthless for this task.
------------------------------------
If you see a lot of high temps on a given tire (outer/center/inner), you probably need a pressure adjustment first. If you get readings within a safe temp range across the tire, but highly uneven relative to eachother, then you likely need a suspension change.

If you see NO temperature, you need to either pick a warmer day, or a faster driver!