greenfrog

This is when having TPMS actually helps. TPMS is not accurate either, but it is pretty consistent. I use my oil filled Longacre analog gauge to set the tire pressure, then I look at TPMS reading to verify that my Longacre is not out of whack. They always differ by 1 psi. I also glance at the TPMS reading on straights to get a quick idea of what the tires might feel for the next lap.

With ambient temperature change, and direction of sun light relative to parking position, targeting a particular hot pressure on all four wheels is an art. Detailed logs using always the same gauge is a must.

BTW the Longacre oil filled analog gauge has a pressure relieve valve to compensate for inaccuracy induced by ambient temperature change.

JP66

I have another hobby where I write for magazines and one topic I cover frequently is testing of parameters. The fact is that all instruments have error and unless you purchase an instrument with a certified accuracy (and often no such "certification" exists) you really don't know what's what.Having said all that I will contrast that with a simple fact: multiple readings from different cheap gauges that are then averaged can usually give readings as accurate as an expensive instrument.

Point is: even a $300 gauge can be off if it doesn't have some type of "certification" but multiple readings from different cheap gauges that have been averaged will normally provide equal or better input. Plus if you know the variance in a given gauge you can account for that, Trouble is most instruments used for measurements of any kind will vary considerably depending on conditions.

Never rely on a single reading if the result is important to your success.

Frank 993 C4S

A good quality tire pressure gauge should be the first purchase anybody makes that takes their car to the track. I always use my own gauge, even with track support so data is always consistent.

RallyeChris

I use a cheap gauge purchased from Harbor Freight. How "accurate" it is, I do not know. But, by reading the "triangles" on the tires and feeling the car's behavior on-track, I have used it successfully to find ideal pressures for my cars. If the gauge reads "30psi" when the car feels best, then "30psi" becomes the target for that tire, on that car, using that gauge. For 95% of DE participants, this method is fine.

If you are looking for that extra tenth or two, temp probes and better gauges become more important. As with anything, delving into minutia can be difficult and better/more accurate equipment will be required.

CCA

You know that the "triangles" are just there as pointers to indicate the location of the Treadwear Bars on DOT tires. They are not intended for use as tire/chassis set up markers.

JCP911S

I'm waiting for Tom Brady to weigh in on this issue....

gobuffs

Digital gauges can be sent off and calibrated. Analog gauges cannot. A digital gauge is expensive but WELL worth it in not destroying tires. (BTDT and lesson learned the hard/expensive way).

RallyeChris

Disagree. While the triangle May line-up with respective wear-bar locations on some tires, the triangle itself is located to reference ideal contact patch/tread use. See links:


http://www.pedrosgarage.com/Site_5/T...igh_Speed.html


http://www.trackdayguru.com/tyre-management.html

stownsen914

A bunch of years ago there was a major Indy Car crash involving a tire blowout that was attributed to a bad tire gauge ...

LuigiVampa

I was listening to the CarCast podcast and Adam Corolla was talking about his crew almost never check and adjust air pressure. He spends tons of money to restore the Paul Newman cars and he doesn't check tire pressure?

If you listen to the mist recent podcast he admits this. Crazy!

Plavan

Alright- I'll acknowledge this......

BAHAHAHAHAHAHA

BrandonH

every serious race team will use temps as critical to fine tune the chassis. The 'some sayers' would be wrong for two reasons: 1) you are using a probe (basically a needle) to measure temps inside the tread carcass, which cools much more slowly than the surface and 2) you care more about relative temps than absolute temps anyhow. Basically you want the temperature to be the same across the inside, center and outside of the surface, and you want to know temps relative to the other tires. So if it cools slightly which of course it will, you don't care.
When temps are optimized, you correlate that with pressures and now you have a quick and dirty shorthand for whether the tire is performing correctly.

Again, that is not to disagree with the first question which is yes you need a tire gauge that is a serious instrument and not a toy...

winders

Well, there are several problems here. First, most of us here are club racers and don't have a team of engineers working with us on our cars. Second, the "relative temps" idea is pretty much all wet because most of us are running radials which have a lot of negative camber. So, even if you manage to run hard all the way to pit exit, you have that time where you are running slow on the inside edge of your tires. That means the inside edges are going to retain more heat that the middle and outside edge of the tire.

For most of us club racers, we can get a good idea from the tire manufacture what pressures their tires like and we can look at wear to see if we have proper camber for even wear across the tread. Most of us don't have multiple compounds to choose from and those that do can usually get info from someone else on what compounds work best for their application.

CCA

No, other way around. They are there to indicate the location of the DOT mandated 2/32 wear bars. While some may have found them helpful in dialing in certain tires, that is not the original purpose. Also, not all tires use the triangle indicator, some use TWI (Tread Wear Indicator), Michelin uses a little Michelin Man pointer. - Aren't they cute? If the purpose was to be used as a tool to judge the ideal contact & tread use, than I'm clueless on how to adjust my truck's tires.

winders

Correctomundo!! There is a lot of misinformation out there, isn't there?!