I've had some serious issues with tire gauges that came to light at work a couple years ago. I blindly relied on a 'quality' gauge that I purchased at a Napa store. It was supposed to be their "best" gauge. Since I deal with quite a few vans and transportation vehicles that carry up to 15-20 college age students, which are often driven up to several states away, I take the safety aspect of this pretty seriously. I also kept a 2nd gauge in the back of the shop for regular campus equipment. One day I had to use it on a fleet vehicle and found that the tire was overinflated by 15+ pounds. NOT good! Or so I thought. I have several gauges at home that I randomly use, so I took them all and tested them at the same time. I was shocked to find that, out of about 7-8 gauges, only 2 of them matched, and they varied by as much as 20+ pounds!! I just can't accept that!
I ended up switching to a digital gauge. They're much more accurate, even testing with other digital gauges. I have, on occasion, ran across random problems where it just won't take a reading from a tire. It seems that, more often than not, it has to do with tires that have low pressure sensors built into the valve stems, but it even happens on the occasional old style tires, and even tube types. In that case, I use a mechanical gauge that I've checked with the digital, and matches it as closely as possible.
For the MT ET Street tires that I have on my Mach, I bought a Moroso tire gauge that only reads to 15 pounds, since I never go over that when they're aired down for strip use. I've found it to be pretty accurate, although it's hard to use since I don't want to put it on the tire when it has 28 pounds for fear of damaging the gauge. I've also found that the more closely the gauge matches the pressure that you're measuring, the more accurate they typically are. In other words, if you use a 0-120 pound gauge, and you're only measuring a tire that takes 10-20 pounds, the gauge is likely to be way off on the lower scale. I'm going to purchase one of their newer digital gauges for my ET Streets also. When it comes to tire gauges, especially with all the cheap crap made today, digital is the way to go. The 2 that I purchased, one for home and one for work, both match in pressure, and they were about $45. Well worth it in my opinion.
