This is the production...

This is the production version of the prototype device we tried in Issue 946. It has clear instructions, and the final caps are smaller than the test unit’s, although they’re still far bigger than standard valve caps.

You programme each of the caps using the digital monitor. Once set, they replace your standard valve covers, and then you can check pressures simply by holding the monitor over them. The result is shown for 10 seconds. But the trouble is, it’s not a precise reading. If a green LED flashes, the pressure is between 90 and 120 per cent of what it should be, amber means it’s 80-90 per cent and red below 80 per cent.

Using our special three-valve test wheel – which enabled us to check the monitor and release air at the same time – we found the kit triggered as it should. But the percentage reading means you could lose 3psi or so before getting an alert. It works better than caps with coloured tags in the tip, but when you’re only saving a few seconds, the ?40 price tag looks fairly high.