Have a question on how to interpret what it says. Seems to me, the temp across the tire would be +/- equal reguardless of hard cornering or not if pressure is corrrect?

I will, if event does not get cancelled due to weather, be heading to an autoX event Saturday and want to get this sorted out prior to my runs. I plan on heading out this week after work and tip-toe through some twisties and figure out what is good starting pressure as it will climb some when tires are hot. Specific info on tires is below.

Toyo R888's:
295/30/18"s on 10"s
315/30/18"s on 11"s

The Jazzer thanks you

 

just set the tires where you want them pressure wise and then let air out as they heat up. that way you're consistent across runs.

btw, i have no idea what a pyrometer does, but it has "pyro" in it, so it has to be fun

 

Silly wabbit

***HERE*** is the one I purchased and is used to measure temperature with a lazer.

 

Geeez, I was confused, too. So you bought an IR thermometer. That's much more clear now.

Looks like the emissivity isn't adjustable. That's fine for shooting your tires and most dark objects. Won't be very accurate on shiny, reflective surfaces, though, unless you can adjust the emissivity setting.

 

How 'bout people not ASSUME.....

A contact pyrometer and IR thermometer are 2 very different things that do a similar job. Which one did "The Jazzer" (are you serious? really?) buy?

Personally, I would say someone with little to no seat time needn't worry a whole lot about tire temps for the moment, especially running on Toyo's. I doubt you will even get them to temp on a typical autocross course. They take long enough on a road course. You're gonna have enough work to do finding a setup on a GR40 car. If you have the receipt I would send it back and spend the money on something more useful at the moment like beer or lap dances

 

My concern is really that I am not under-inflated and understand that tire temps will get higher on outter/inner edges if so. Am I incorrect? I know I was rolling over on my Winter wheels/tires due to under-inflation and want to be a little more diligent to get the most of my available traction.

EDIT: I realize that I will not reach optimal temps on an autoX, but reach it consistantly on roads like this on Sunday:



My goal is to find the optimal pressure for my typical driving, as above, and will be helpful in the autoX.


I realized after I posted that it is really an IR thermometer, but unable to correct it with latest MF software.

 

I've used a contact pyrometer a couple times and it worked very well. I've read numerous times (corner-carvers, corvettforums) that the IR ones (where you do not actually insert a probe into the rubber) are tricky to use and can give misleading info. You may want to return it and get the probe type.

For this AX you can probably just set those tires at 30lbs cold and not worry about them. You will overdrive the car anyway (its a guarantee, every rookie does it) and heat up the fronts and/or power oversteer and heat up the rears. The readings you take are not going to be valuable because of this - they will reflect your driving rather than the car's setup. My advice is just forget about temps. At 30lbs those tires will not roll over and will have plenty of grip. Hell with that low of profile they probably wont roll over at 20lbs - LOL.

As for your nice looking trek through the Napa area. At the end of it the inside, middle and outside should all be reasonably close. I've been told within about 10-15 degrees. If the middle is significantly hotter, you are over inflated. If the outside is significantly hotter you need more negative camber (assuming you were not overdriving the car). Norm, Sam or Rodeo can probably give you a little better understanding of how to read the temps.

 

Thanks Argo

Just now tried it and you are correct. Depending on what angle the lazer meets the item being tested, the temp will vary. I think I will take yours and Radio's advice and exchange it for a contact pyrometer as I am sure it MUST be more accurate. Kind of bought it on the fly anyway during trip to Napa Auto for a new mechanical tire pressure guage.

 

IR pyros are pretty much useless for taking tire temps. They only measure the surface, and just the sun and shade can change the surface temps. If you want to take accurate tire data you need a probe type pyrometer (watch any tire tech at any race track, you'll never see an IR gun).

As for tire pressures. If you are far off, you'll see it in the way the tire wears. In fact I don't even bother with temps anymore because they don't help me a bit, and the last time I did a test (on a 200' skidpad on 315 Hoosier's) a 10 psi change didn't have any effect on the temps across the 3 sections of the tire. If you are in the range that makes the tire hold it's shape, that's all you need. And from a grip standpoint you run as low as you can until the tire deflects and causes you to lose contact patch (which you can see by wear patterns).

And fwiw, you will generate more heat autoxing than on the street unless you are just putting around the autox course or completely insane on the street. It's cornering and brakes that put heat into tires more than just running straight. I can't think of more concentrated cornering than autox, and I can't think of anything that puts heat into a wheel/tire like running on a road course.

 

Thanks, Sam. I ended up returning the IR thermometer today and exchanged it for 8 qts. of Mobil 1 full-syn. and filter. That alone just about ate up my entire refund . It was all over the place as far as accuracy anyway.

I have been running 30 PSI cold and have a very good feel for how it turns under this pressure under very high stress turns. It does seem to roll over a bit from the feel, but not alot of sidewall indication. I jacked 'em up to 35 PSI cold and will take a cruise and heat 'em up and see how she does. It is a high enough change that it should be obvious if I was running low or not and adjust as necessary.

I will test PSI when nice and toasty and see what I gain pressure wise. My goal is to find a nice PSI and leave it alone as, 'til this point, I have only driven street. If I want to do more autoX or hit the track, I may have to experiment with pressures a bit to find what works best.

For now, my autoX is this Saturday, so I am just going to put a heavy-duty screen all around my ride so I just push the cones away rather than suck them up under my ride