Anyone have any experience with the inexpensive (about $15) digital tire guages that Radio Shack sells? I've got one which i purchased several years ago, and it has always seemed reliable -- it gives completely consistent readings when repeatedly checking the pressure in one tire.

 

However, I just bought new tires, and the guage attached attached to the air pressure hose at the tire place gave much lower readings -- the tire people inflated the tires to a claimed 32 psi (i checked with their air hose, and got readings which varied between 34-36 psi), while my Radio Shack guage showed 38 psi on the same tire!

 

I'm suspicious of the guage on the air pressure hose at the tire place because of the inconsistent readings - a 2 psi variation when repeatedly checking the same tire - but I'm surprised how much higher the readings were on my Radio Shack guage. And you'd think that a place that sells tires as its sole business would use an accurate guage!

 

Zack

'90 Legacy wagon AWD auto 158,000 miles

I've had their cheapest gauge for 3 years or so. It's self-calibrating (against atmospheric pressure) and has a stated accuracy of 0.5 psi. I'd trust it more than the gauge on the hose. I believe all digital gauges use the same circuitry. But one thing I don't know is what happens when the battery ages, although the gauge should indicate when it's low. Maybe I should replace the battery just to see if there'll be any difference in readings.

I have one too,

 

I have always found it to be accurate.

I think the digitals rely on the changing resistance between two thin sheets of metal, when one is bent by air pressure. Not much to these, not much to go wrong, pretty reliable until the battery is dead. Don't forget tire pressure goes up pretty quickly with heat, easily 5-lb higher from normal driving. You should go with the tire pressure recommended on the car (not on the tire) and check it cold.