I recently bought a used car. When I checked the tyre pressure, one of the tyres was over inflated by 16psi. I let the air out to the correct pressure, then checked them all again a week later. The same tyre had increased in pressure by 6psi. How can it possilby be inflating itself? Any possible explanation would be greatly appreciated. I've never come across anything like it before.

Rob, December 2006

Chances are it's the gauge thats reading differently. Tyres can't self inflate. They can move up by a couple of pounds when hot. You should check them cold at the same place with the same gauge. DIY push on guages aren't 100% reliable, use one at a garage.

MOT Andy, December 2006