The Schwalbe Airmax Pro digital tyre pressure gauge is very precise. It measures the pressure up to 11 bars and is suited for Car (schrader) and Presta valves. Also with the conventional bicycle valve the air pressure can be measured, however, only in combination with the Schwalbe Valve insert.
Tip: Check your tyre pressure at least once a month with a tyre pressure gauge. The famous check with the thumbs is completely unreliable. Even with half of the needed pressure tyres will feel hard. Insufficient tyre pressure is very common. The result is dramatically increased rolling resistance and premature tyre wear.