Last year ( at Popham ) bought a couple of s/s tyre pressure indicator jobbies from one of the tented vendors. Looked the businesss, and had factory pre-set pressures. Its the ones that are screwed onto the valve , and indicate the correct pressure with a green indication. Supposedly, when the psi drops off by 2 psi. the colour changes to orange and then red, if it drops even more. Trouble is they are rubbish. Been green all winter, tested the press. today with accurate guage and RR had dropped off by 4.5 psi. and FR was off by > 2 psi. Still showing green as gooseberry, but I reckon these things may be OK for the tin-box but not that good for two wheels where tyre pressures need to be spot on. Perhaps I am being moronic to expect them to work as accurately as the advertising stuff says. Erm ?
Fitted some last year and had the same experience, sent them back with the details and got a refund. Never got any feedback as to why they didn't work, but would never fit anything else like that again Just back to kicking them again now