My mate has just sent me a link to a website where you can get a free tyre pressure and depth gauge so that you can check the depth of tread on your tyres. Should help you avoid the Rozzers :)
Get yours now at: http://tyresafety.eu/order
Normally there is a spring (leaf spring?) attached to the pressure regulating valve so that the rear brake wont lock (in theory).
On my corsa this spring corroded and is now loose, is this dangerous ? Could the breaks lock without the spring or will the valve still work but with less...