It’s worth noting that you can get different air-pressure readings depending on which garage forecourt you use when checking your tyres. Trading Standards says drivers have the right to expect an accurate reading (where they pay for the service) and that gauges should be recalibrated at regular intervals, ideally every six months. However, this is often not the case.
Also, many handbooks list pressures for cold tyres, but when you drive to the garage, the tyres warm up and pressure increases. So even with an accurate gauge, you are likely to be underinflating your tyres. The solution is to buy a gauge and check the tyres yourself – a combined digital gauge and pump costs from around £20-£35, for example, at Halfords.