0 a measurement of how much air is in a tyre:
There were countries which had problems with measuring the weight of ships, or alcohol meters, or tyre pressure gauges.
The inaccuracy of the tyre pressure gauges on many garage forecourts is frustrating.
These include tyre pressure monitoring systems, wet grip requirements and lane departure warning systems.
Once a car has been connected to the net, it would be possible to give the driver information on tyre pressure.
A tyre pressure gauge is supposed to measure the pressure that is actually in the tyre, not what one would like it to be.
The adoption of such a scheme would enable road users to have full confidence in tyre pressure measurements made at service stations.
Most tyre pressure gauges are at present marked in pounds/ square inch, though gauges indicating kg/cm2 also are not uncommon.
Some variation in tyre pressure is acceptable because manufacturers recommend for individual types a range of pressures varying with the load carried.
