[Speedy]

Beat me to it, first and cheapest thing to check. Don't forget check them when they're stone cold preferably before you go out or make it the weekend. I've got one of those compressor gauges but then always check with my trusty pencil gauge, you can actually feel the difference when they're over pressurised and I suspect that's whay your experiencing?, just find out what the stated pressures are in the handbook or fuel flap.....

Steve.