Your post does not make sense.

"and the tyres appear to inflate again."

Impossible.

And putting WD40 on brake calipers? You are either winding us up or trying to kill yourself. Brakes and oil do not mix.

You should take it to a competent garage and get them to look att it: you appear a danger to yourself..

Edited by madf on 27/01/2011 at 14:16

madf was being a bit harsh-calipers move, a little oil on moving parts is not a bad thing! If you have a sticking brake, clearly, the disk and caliper will get hot. If the heat is transferred to the wheel, then the air in the tyre will heat up and, corrospondingly the pressure will also rise. The additional pressure could exacerbate any slow leaks. As the tyre cools down, the pressure will fall below what you started with-hence the tyre is flat. All perfectly consistent. Testing is quite easy. Just go for a gentle run on a quiet road, and avoid using the brakes (use the gears if necessary) as much as possible. Pull over and immediately feel the disks. They should be hot to the touch but not burning hot.

Cheers folks, all makes sense now. I drove it gently home from work (couple of miles) and the brake pads were smoking when I got home.

Pulled it off the road and will wait for recovery to the garage. Excellent advice not to drive it any more! Looks like the disc is well worn (large lips around the rim) and will likely need replacement anyway. maybe this has contributed to the pads jamming up.