Well if I'm going to check them I'm probably going to fill them so I just use the gauge on the air hose.
I have Civic Hybrid with two lights, one for low air and one for TPMS malfunction. I have to check this, but I think on Honda cars when TPMS light is on, the system no longer works. The rest of the good TPMS sensors are not being monitored.
Tire pump! Prius tires are small, so a regular bicycle pump will fill them quickly and easily. Or get an electric one. Under $30 last time I looked. You can't get an accurate or correct reading with hot tires. Read the manual, it will say COLD tire pressure. I "think" the tire says that also...
Just a word of caution. Those gauges on the air house, especially ones at gas stations are notoriously inaccurate. $5 manual tire gauge is far better.
I've never trusted those. It might be accurate, who knows. Research pressure gauges. They can be a mixed bag. I prefer a simple stick gauge. I've bought a few lemons too: a gauge can look fine, but be maddeningly hard to get a good seal on the valve stem, for example. It should be reasonably accurate, and consistant. That's what I'm using. It's a bit of a work out, but it's cheap, and it works. I've even brought tires back to pressure from dead flat, after a repair.
Yeah, my son has been driving my HCH with TPMS light on for a while. Last time I had the car in a shop for the winter tire change, a technician told me not one but two TPMS sensors are bad. I did not want to spend $100 to fix them, so I told them to leave them. The car is now with two bad TPMS sensors, and two good ones left. We have not seen low tire pressure light on the car since TPMS light came on. It would be easy to check. I will let air escape down to 20 psi on all four tires, and if the low tire pressure does not come one, the entire system is off.
Checking them periodically is important. But needing to drive to a gas station is a major disincentive to doing so, and very few people who don't have their own, check frequently enough to prevent needless tire damage from under inflation. The gains from having the convenience to check at home greatly exceed the cost of buying your own gauge.
We go to the gas station anymore not the service station. There is no oil or air on any gas station islands I have been to for years. Air, out of sight, out of mind.
In CA, stations no longer charge fees for those self service air pump thingy. When the law passed, a lot of stations removed the air pumps or left in-operable because the up keep cost wasn't worth it anymore. It used to be $0.25 back in my day to get air.
