either way, it's still $20

I typically use a tire (tyre, to you Brits) pressure gauge in the car, when I remember to check the air. Often that's about once a month, unless I notice the car's a bit sluggish taking a corner.

So, when it came time to replace a front floor mat, I spotted (nearby) an acceptable price on a set of Indicator Valve Caps for the tires (Tire Check, by Kleen Wheels). Now, as I'm approaching my parked car, I can glance down and see when one/more of my tires has lost enough air to merit a stop at the air pump. The indicator is difficult to master: green=good and red=bad. Golly, I hope I can remember this. The set of four was $20.

Speaking of air, I recently asked the "experts" about the trend of some car service places to fill tires with nitrogen instead of "plain air". The merchants claim that the nitrogen molecules are larger, and hence won't leak as fast. For $20 (i.e. $5/tyre) that should be true, but my local experts say it's basically a marketing ploy (i.e. "crap"). Maybe if I was driving a racecar around Texas Motor Speedway, but not on the way to the market.