I'm hoping that by getting one I'll be able to better dial in my air pressure, alignment, and maybe even extend the life of my tires a bit. Seems like a no brainer, but I thought I'd quickly check in here to see if it's a worthwhile tool and not a gimmick for my application - just DE's so far in a street/track compromise car. They seem to be going for around $100 for a digital probe type meter.

TIA,
Drew

 

Definitely the right thing to do. I've wanted to do this but unless you can get out of the car safely and take the temps and pressuree quickly after a hot lap, the readings won't be accurate (my understanding; no actual experience). So ideally you would need an assistant who can do it in the hotpit, especially if you are in a harness and H&N restraint that makes it almost impossible to do efficiently by yourself.

 

Any idea of how quickly the tires would cool off to make this exercise worthless? I was hoping that since the probe-type meter takes the temps sub-surface it will give me at least a 5 minute interval to take meaningful measurements.

Also what about the legistics of how to properly use one? I mean are you supposed to pit off the flying lap? If so what if the pit entry is at the end of a long straight? Should you do easy braking before you pull in?

Hopefully someone with hands on experience can chime in. I know it's a relatively cheap tool, but I'd rather keep my hundo if the tool will be of no use.

TIA,
Drew

 

The outside of the tire will cool very quickly (thus making those IR pryometers very misleading). The inside will retain heat better. This is why traditional pyrometers are needles that you slip into the rubber.

The suggestion from the Toyo engineer that Chris Bender reposted was along the lines of "if you want 200 F and you are reading 200F in the pits, then you are running too hot on the track". He didn't say if there is any rule of thumb to estimate this. I would guess Carrol Smith has something about it in one of his books.

 

I use it and I find it is an invaluable tool for getting the tire pressures right on a track new to you.

I haven't found that it doesn't make a bit of difference to wait until I pit and get out to check the temps. You are looking mostly to see differences across the tread rather than absolute temps. I take 3 readings per tire. From that I can tell if I need to go up or down on tire pressures. Ideally you will end up with even temps across the face of all 4 tires. Probably your front tire temps will he higher than your rear tires.

A high center temp tells me that I have too much air pressure in that tire. Once I get the tires working right I let it be. It usually only takes a couple of readings a day unless I have just changed brands or types of tires.

After everything is cooled off you can take the cold tire pressures and that will give you an excellent starting point for the next time you run that track. Keep in mind that air temps will have an effect so if you are running on another day where the temps are higher you would probably start with a pound or 2 less and then check them. If temps are lower you start higher.

At most tracks and autocross events I find one tire (usually a front tire) ends up with more pressure than the rest. If there are more left turns then the right front usually needs a pound or two more than the others.

Yes, it does take a minute or two, but it is much better than trying to work around squirrely handling and trying to second guess everything. Get your tires right and then if it still ain't working for you either try a different driving technique or change shock settings, etc.

Change one variable at a time. I have found I can make more good things happen at the track by making sure the tires are doing their job than any other change I can make at the track. Between track events is the time to make changes to the car.

Your cold tire pressures (and how it handled at the event) can even help you identify how to change your alignment settings to help tailor the handling to preferences.

 

I couldn't agree more. (tire guy of course) If you can't get the tires to work properly then it makes no differnce how much you've spent on engine upgrades or for that matter suspension. As a track support tire shop, many times what we here is "these tires suck or somethings wrong with the tire." 99% of the time the tire is fine. In fact the tire is one of the only visual ways to see how the car is handling. The post above does a good job in explaining some of the visual things to look at. I also agree if getting a basic car setup for track days is what you might be after, then don't break your neck getting out of the car. The tire will cool pretty uniformly so your readings though not completely accurate will give you a reading of the way the car is working.

You need to take temps on the left, center, right of the tire. Most tires will cool down about 20deg just coming down the pits. If you have help, come in hot! This will give you the best chance at the most accurate numbers.

That said, just look at the tires after each run and you can usuually see how the the tire is wearing. Most track day cars don't have a lot of camber adjustment, so you will need to watch the wear,especially the left front, and flip the tire on the wheel to even out the wear. Now that said, if you are running a Hoosier or the like, flipping may be ok, but if you've already cycled it out, it does next to nothing.

Oh, if you have a tire that is wearing on say the inside and not the outside, that means the tire is not making even contact with the track. Make the proper adjustment. When one side wears faster thant the other that is a visual that the setup needs tweaking. If you can't tweak further, then that is when you need look at flipping the tires or just moving them around to a different position on the car.

Tires are your best friend on the track. Taking just a few minuites to look them over can really pay in traction and lowering your times.

 

thanks, sounds like a usefull tool. i'll pick one up.

 

A minor nit: as the Toyo rep pointed out, aiming for even wear and even temps across the tread is the best way to extend life, and a *good* way to set up the car, but it's not the *fastest* setup. For that last tenth or two, set up the car with slightly higher inside temps, so the tires are properly (evenly) loaded on fast sweepers, which is where you'll gain the most time on track. It's a subtlety, and the downside is reduced treadlife, but if all-out speed's the goal, you gotta use every trick in the book.