All owners of wheeled vehicles - motorists, motorcyclists and cyclists - have to monitor tire pressure. For each type of transport, there is a range of optimal pressures, which, among other things, can be found by marking the rubber.
Most often you have to deal with units of bar or psi. Pressure in inches per square meter (psi) is used to mark tires made in England and America. Ba r is a unit for measuring pressure adopted in European countries, including ours. It is almost equivalent to the technical atmosphere.
Most modern pressure gauges have a dual scale, on which you can immediately see the pressure in bar and in psi. There are also
electronic gauges for motorists, they select the desired display mode. But the translation of psi into bar and back has to be done quite often, since not every motorist has measuring instruments.
For a single calculation, it suffices to use the equality:
1 psi = 0.069 bar
1 bar = 14.504 psi
An accuracy of three decimal places is usually not required. In most sources, you will find that 1 bar ~ 15 psi. But the higher the pressure, the greater the error in the calculations according to this approximate equality. Therefore, multiplying by 14.5 is the best option.
You can also transfer pressure from bar to psi using special electronic pressure gauges, which are sold in stores for car enthusiasts. But if there is no such device, and the conversion of psi units to bar and vice versa needs to be done often, it makes sense to make a table. Garages use tables with a step of 1 and 0.1 bar or from 5 to 15 psi. And if you have access to the Internet, it’s easiest to translate the value using a search engine calculator.
Measurement errors
Tire pressure is quite dependent on temperature, so the pressure gauge will differ in the warm and cold season, even if the same volume of gas is pumped. The tire also heats up while riding, from friction against the road surface.
Measurements are usually carried out “cold” when the car drove no more than 3 km at low speed or stood for at least 2 hours. When the condition was not met, it is necessary to subtract 0.3 bar ~ 4.5 psi from the readings. The pressure measured in winter and summer can differ much more: with a decrease in temperature for every 5 degrees Celsius, the readings decrease by 1 psi.
A car or motorcycle tire naturally loses about 1 psi each month
(pressure in a bicycle tire drops by as much as 15 psi). Thus, with a smooth increase in the average monthly temperature in the spring, it is often not necessary to inflate car tires. And in the fall, and especially with a sharp cold snap - this is the key to safety on the road.
It is sometimes difficult for a layman to determine the exact pressure, since in mechanical devices an error almost always appears. Now you can buy manometers with “smart” microcircuits, which make adjustments for temperature. Is it worth it to purchase a multifunctional device, trust your intuition or the skill of an employee of the service station - you decide. The main thing is that the tire pressure is suitable for a comfortable and safe ride.