Most vehicle placard pressures haven't been 30-32 since the 1970s. Unfortunately, the myth of 30-32 psi is still strong in the automotive service industry so millions of tires are under-inflated. TPMS doesn't help because, unless you change it, it's set at the factory to alert when the pressure is 25% low. In other words, when it alerts the tires are already in a serious world of hurt.
Something to know about tire pressures:
1. All load/inflation tables are based on 65 F (18 C) ambient temperature. If the day is hotter than that you need to adjust the pressures upwards to compensate (there are charts). If it's very cold out, inflation is done in a relatively warm garage or shop and the inflation pressure needs to be adjusted upwards to compensate as well.
2. The vehicle placard pressures are based on the typical load the engineers think the car will be used at. This may not be the full GWV. On a vacation trip you have to compensate for this.
3. Pressures need to be raised to compensate for speed. Presumably cars expected to be driven fast such as the Model S already have this built in. However, family sedans typically have pressures based on a maximum sustained speed of 65 mph. Go faster and you need to increase.
4. The load inflation tables are based on a pressure check every driving day before you travel more than a mile (slowly). If you don't check your pressures daily, then you need to compensate so that they never go below what they should be.
Heat kills tires, not pressure.
Don't exceed the cold pressure maximum on the sidewalls when inflation tires first thing in the morning.
Get a good pressure gauge. This means spend $70 - $150 on one. A good gauge can be calibrated and will last a lifetime. Digital is more expensive, but not more accurate.
Can you provide some examples of "good" pressure gauges? Thanks. Shopping for such things gives me something car-productive to do while waiting for the call.
