The 2 back tyres on my mk3 genesis look fairly well inflated with hardly any "flat" at the bottom. However I pulled into a Supermarket to check the air pressure all round and the 2 fornt tyres are 28 psi but the back 2 only register about 23 and 24 psi on the gauge.

Is it possible for the valves on the tyres to be giving a wrong reading as I really dont wanna blow a tyre out at the filling station or do the rear tyres always look full even at a low'ish psi because they're not supporting an engine.

Cheers for advice........

Not really sure on the accuracy of the gauges themselves but don't forget your tyres are going to be warm if you've driven to the petrol station, and the pressure should be set when cold. However as I understand it warmer tyres will give a higher pressure reading, so your pressure would be even lower than what they say when cold. I bought a Michelin footpump from halfords and use that, I also have a digital keyring-type gauge but it doesn't give a very good reading any more, but when new it was pretty good and I don't think they cost more than a few £ (mine was a gift).

I don't know much about valves but I suppose if they're not opening fully then any gauge would read lower than the actual pressure.

Warm tyres do make a diffrence in psi. I've tested it, cant remember what the psi was before and after but mine were about 7 psi diffrence warm to cold.

I use whatever airline i can get my hands on.I bought a

Trye Pressure Gauge from work and every time i put

air in ,i check it with the gauge just to be sure.

Tbh filling station inflaters are shit and can be up to 0.3 bar out.

they aren't mega accurate but a lot more so than looking how flat the tyres look. just pump them up to 26.

It really depends. Normally I find that the ones that require 10p/20p for 2 mins or something are more accurate than the ones that are free as these are usually more used and abused.

I once went to fill up in a free one near my house when I had my old MK4 Polo, it showed 10psi when the tyre had 30psi

I now just use my own digital tyre inflator instead, they are quite cheap!

Yeah as above I just bought an inflator. Got a mega-accurate digital gauge as well that I pinched out my dad's racing toolbox.