Tire Pressure Gauges: What is reality anyhow?

lokki

I'd given up my pencil type air pressure gauge that I'd always trusted and purchased a made-in-China digital gauge for $10. Figured it is accurate and I've been a happy little camper, running around keeping my Michelin pressures nice and accurate.

However - this week I visited a Brookstone store and was tempted into buying a beautiful 'Gauge-style' "Precision" tire pressure gauge supposedly accurate within in 1 PSI. Great. Brass and Black with a nice white dial-face Much prettier than my cheap black plastic Chinese digital gauge.

Only one problem: It consistently reads 5 PSI higher than my digital gauge.

Which one is accurate? My brass Brookstone "rugged tire gauge consistently accurate to 1 psi. with laboratory-type bourdon tube and fully-geared brass movements "

Or my cheap Chinese digital guy?

Or neither? How can I check? 5 PSI is a lot. I'm either running 35 PIS in my rear tires right now (manufacturer's heavy load setting) or 40 PSI if Brookstone is right?

fleetwoodsimca

My very old Acme truck tire gauge had been getting "sticky" and changing its mind, you might say. I replaced it with a new gauge made in Muskogee, Oklahoma, and sold as a NAPA product. It also has the dual-end head that earns it the "truck" designation. I have to go with the new one, which shows great consistency, and a couple pounds heavier readings than the old gauge. Wouldn't it be great if we could go to a place that had a known pressure for us to test our gauges? Fat chance of that, I reckon. >:o{

speedshift

I guess the bottom line is how well the car rides and handles and whether the tires are wearing prematurely due to under- or overinflation.

Five psi should make a big difference in handling and ride. I'd keep the tires where the ride/handling balance feels the best to you and watch the wear pattern. If the tires are starting to wear more in the middle they're overinflated. If the cars feels squirrelly they're underinflated.

bretfraz

AFAIK, the only way to truly know if your tire gauge is accurate is to compare it to a calibrated unit. I own both the digital type (Accutire) and the dial type used by many racers. Comparing both show pressures are virtually identical but how do I know if they're both accurate or not? Without a calibration I don't.

q45man

http://www.dwyer-inst.com/htdocs/pressure/65000.html

If 3% of FS is enough total error 1.8 psi on 60 psi unit

http://www.dwyer-inst.com/htdocs/pressure.html

The have units available which will be 1/4 of 1%

I have 6 different units the electronic is by far the best repeatable and accurate


It is amazing owners would trust a $1.99 gauge, we tested the $25 units [each tech has] used to air our customers tires they varied by over 5 psi one was 8 psi out of range!

http://www.dwyer-inst.com/htdocs/pressure/475-FM.html

fleetwoodsimca

The practical truth must lie somewhere in the territory of consistency from tire to tire on the same vehicle, more than being very close to 100% accurate.
What is the creme-de-la-creme of tire pressure gauges? (type, brand, price, availability)

q45man The Dwyer site looks very interesting. Can you shed some light on it?

speedshift

I think you're right, for a daily driver it's consistency more than anything else--the front tires are the same inflation, the rear tires are the same inflation, and the gauge performs consistently every time you check pressure.

As long as the tires are within the manufacturer's recommended range and satisfy the driver's ride and handling expectations, that's more important than whether the tires are inflated to 28 or 32 psi.

I guess even if you were seting up a chassis for racing you'd be okay if your tire gauge was consistent but inaccurate. The consistency would control the tire pressure variable. But if you were talking to the tire engineers you'd want a dead accurate gauge, since we can assume theirs are.

dudleyr

There is a long discussion on tire gauges in the Aftermarket and Accessories board that might be of interest.