Just checked my tyre pressures on the bike, car and van - scarey stuff! All 3 were down, the bike's rear was 0.4bar below what it should be and the front 0.2bar below. The van...well almost 1 bar below on each of the rear tyres, and all 4 car ones were well below too.

I really should check more often...I'm very bad at doing basic maintenance and check maybe twice a year