Is there an extra charge to use Nitrogen instead of Air ? Some Owners' Manuals recommend checking tyre pressures on a regular basis, even once weekly. I check mine about one every two to six months, and very seldom do I need to top up. As well, when the cars get serviced, part of that service includes the checking of tyre pressures. Last time Cappie was serviced (Captiva) I noticed for about two weeks some harshness in ride comfort - when I checked the tyre pressures, the reading was well in excess of forty pounds per square inch in each tyre.
Reducing the pressure to 35lbs. all round restored ride comfort to a greater degree - it must be said that Cappie's suspension does not provide the most comfortable ride - although the faster you go, the better the suspension becomes.
With Gleaming Beauty (6.9) on account of its fitment of very low profile tyres, maintaining steady pressure of 36lbs. all round is of utmost importance. Again, once a month in this instance. Regards Styria
N.B. More of Gleaming Beauty in due course.