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I use a Longacre dial gauge at the track. I would use a digital for convenience at times, but all of them I have tried (From $10-$40, including the Craftsmen mentioned above) only seem to measure to .5 pound read outs. It’s 30.0 pounds then it lowers to either 29.5 or jumps to 30.5. I would like them better if they were more accurate. Am I doing something wrong?
I completely agree with you... I was just saying that if I'm going to drop $50 on a nice solid gauge I'd just prefer that it also be reasonably accurate. I personally like the LongAcre mostly because I can slightly overfill the tire then use the bleed valve on the gauge to get to the reading I want. I also like the solid feel and rubberized edges. The bleed valve on my prior cheap gauge failed within a year.
When I autocross there is no one magic number that I must absolutely hit... maybe I'm just not that good. I just like all of the tires to be the same left to right and in right ballpark for what I'm expecting.
If you like the bleed, which is a great feature, then you will probably love a gauge like Griot's sells that connects to the air tank allowing you to flip between adding air and bleeding at the press of a button.
There is a rather wide range of roughly 28 to 40 psi within which the vast majority will be happy and maybe even swear by. I'm talking operating temp pressure. Cold readings are meaningless except to the extent that your normal driving results in only a few psi increase. But drive that same setting on the track, it can easily go 10 lbs higher. No problem if you set 28 cold because you like the ride at 28, a hard hot track day brings it up to 38, no problem. Above about 40 however the tires get real hard to the point you actually lose traction. Happens to a lot of guys. Within that range however, even though the tires do respond differently every tiny little change the differences are very hard to notice in normal driving. In my experience it takes up to a few years of track or autocross to develop to where you are able to connect and relate and really appreciate the meaning of what I just said. That is, if you apply yourself, seek out the help of advanced drivers, listen, and learn. Some drive for years and never do get it.
The best method I have found, autocross or track, check your pressure immediately just before each run. Bleed out whatever it takes to get back to the same numbers each time. Track driving puts a lot more heat into everything so bleeding immediately after a run is even better. You'll figure out which you prefer as you go along. Main point is just to get really familiar with exactly how the car feels with the tires at this one setting. Until you do this and get used to this it is really hard to appreciate how much of what is going on is due to tire pressure, because you're always driving this range instead of always the one setting. Then, once you have done this for quite a while- and I mean like several autocross events, not several runs- you will be in a position to be able to notice and evaluate a change. I have never met a single driver who was able to do this without going through some kind of similar learning curve. Being systematic like this makes it a whole lot more efficient.
Another thing you can do, especially for people who don't want to track or autocross- go find some relatively deserted stretch of road somewhere, preferably with a lot of tight turns. Dramatically overinflate your tires. Something like 40/45 will do nicely. Take a few corners real fast. Notice how darty and responsive the car is, also how easy it is to slip and slide. Bleed out to 35/40. Notice it is almost as responsive but now grips a lot better. Bleed out to 30/35. Now you are within a few psi of ideal. Bleed out to 25/30. Notice the car responds slower but sticks like glue. Now at this point if you see a pothole don't be Nick Murray, drive around it. And go add some air. You're a little low. But it was worth it for what you learned.
Why, if digital is more accurate? Or are you saying it's just your preference not to have digital?
I have the 100 psi digital gauge from Intercomp that others have referred to in this thread. It is somewhat delicate and requires two hands to operate when checking tire pressure. Also, the hard-plastic carrying case, similar to that of a small cordless drill, is too big to be kept in a toolbox or glove compartment.
I can vouch for the Intercomp digital gauge to anyone who is willing to spend money for good technology, but this gauge is overkill for most people. I originally purchased my gauge to troubleshoot a problem with tires that were being damaged by underinflation.
From my limited experience, the Intercomp digital gauge is a high precision, high accuracy instrument. It is not possible to achieve the same repeatability and accuracy with an analog gauge.
If you want to have some fun (as long as you think arguing is fun) get several people together with their tire gauges, and have them measure the same tire. While some gauges may start out as accurate, time, use, and abuse will change their calibration.
Sobering enough to use 2 or 3 different "quality" personal gauges, and see variance of 10% or more.
On accuracy vs. resolution. Scientifically speaking, accuracy is a measure of how accurately an absolute value is measured given required resolution. Resolution is defined by spec, accuracy is an attribute of a measurement.
What is also important (and for the pressure gauge is perhaps more important than accuracy) is precision. Precision is a closeness of consecutive measurements to each other.
A measurement could be precise but inaccurate.
Love this one…though also have a compressor that has a built it, turns off the air at the entered pressure (though off by 1-2). Cheap digital got new batts and works again, but I just love the classic…its, uh, classic!
from suncoast, little pricey, but neat. high quality.
Update, I went a little crazy and picked up a few. The craftsman digital for the glove box, and a Joe’s Racing and Longacre mechanical 2 1/2” gauges. I picked up the Joe’s first, then the Craftsman, the digital was .5psi higher, decided I needed the Longacre also, got it, and it’s dead on accurate with the Joes racing gauge. Both the Joes and Longacre have the hold/bleed valve, like both so I am keeping both, will most likely put one in my wife’s M4. Also got 2 of the Milton pencil gauges, one is dead on with the Joes and Longacre, one is reading 1psi higher. I marked it such, it will ride in the Prius.
02-28-2018, 07:08 PM
