It is appropriate to do a quick vehicle inspection on occasion. It would be good to know if a tire needs air. Is there a way to know without having to use a tire gauge?
2That will be difficult. If you know your car and these tires then you may know how a tire with enough pressure looks like, but it will be still very inaccurate method. So I think this is not a good answer to your question– vladizMar 8, 2015 at 10:07
It's good to do a walk around before driving off. A tire may have gotten a nail and gone down. People who don't look at their tires may drive for several days on an underinflated tire and ruin it. Usually people detect underinflated tires by handling.– subjectivistMar 8, 2015 at 16:24
Visually I agree it is hard to determine pressure, but you should be able to detect if there is a major difference in pressure on wheels by comparing front or back wheels (or if you have a flat)– holroyMar 16, 2015 at 16:26
If it says 32 psi I usually run them up to about 40, then even if they leak I can catch it in time. I do this in summer, not when there might be snow. Did you read Fear and Loathing in Las Vegas?– user13683Apr 28, 2016 at 23:00
Thump them like truck drivers do with a small bat or hammer. They will make a different sound if they are low, you can also look at how squat they are. Look at the tread and how it is wearing. Over inflated tires will tend to wear quicker in the middle, under inflated tires tend to wear quicker on the outside of the tread.
Gauges are cheap typically less then five bucks for a simple one that will do the trick, and also most places you can get air have a built in gauge, although these gauges are notorious for being inaccurate.
1If it is a newer vehicle, with sensors, you can use a script with the proper antenna to receive tire pressure info from the relays in the tire. I will go looking for it. There is a github that has the source. Video I watched on hak5 a mac was used, but I don't think required. Just need the appropriate antenna I believe– geoffmccMar 8, 2015 at 14:48
If I was going to bend down and use a hammer I might as well use a gauge, and would more likely have a gauge than a hammer. When I was a kid and worked at a filling station I could tell how much air a tire had by looking, plus or minus 5. Mar 8, 2015 at 16:19
2I would say if you have a long enough thumper you don't need to bend down. Lots of things work like kicking or an ice scraper as example. Also if your car is pulling or steering funny might mean you have a low tire.– JonMar 8, 2015 at 21:10
A gauge is best, but gauges on gas station pumps are often inaccurate.. Looking at low profile tires can be deceptive.
By pressing on the sidewall with a thumb, I get a better sense of pressure than by looking, but accurate only to ~30%. Kicking the sidewall (gently) can be used to make a tone, similar to the hammer, but I wouldn't expect better accuracy than by pressing.