A smarter tyre cap
The LED Alert Caps replace the plastic caps on your car tyre valves. To use them, you must first make sure the tyre is inflated to the recommended pressure for your vehicle (check the owner's manual or the label on the door frame), then simply screw on the LED Alert Cap and tighten it with the supplied key. The cap calibrates itself to the tyre's pressure (calibration is permanent once this is done, hence the need to have the tyre at the correct pressure before screwing on the cap). If the tyre pressure drops by 4psi (about 28kPa), the LED on the cap flashes red, warning you to top up the tyre.
We tested the LED Alert Caps on tyres of different pressures; 31psi, 41psi and 50psi. The caps on the tyres set at 31psi and 50psi both began flashing when those tyres lost 3psi of pressure – a little sooner than the claimed 4psi, but a good result nonetheless. The cap on the 41psi tyre only flashed – faintly – once the pressure dropped by 7psi, which is not so good; that tyre would be quite underinflated. The distributor said this problem hadn't occurred before, and pointed out that some warning is better than none at all. Possibly the integrated battery in this cap is going flat; if you experience a similar problem with newly purchased caps, we suggest you return them under warranty. Claimed battery life is three to four years when tyre pressure is properly maintained.
As an anti-theft feature, the LED Alert Caps can only be removed with the supplied key, which is rather small and requires several turns. Keep this on your car key ring so you don't lose it, though the Tyrechecker distributor claims they'll provide a replacement if needed.
While not all the caps we tested worked exactly as claimed, and are a bit fiddly to remove, Tyrecheckers LED Alert Caps are definitely worth considering. By helping keep your tyres at the right pressure, they're a step towards safer and more economical motoring.
$34 for two-pack; $67 for four-pack (for light vehicle set, tyre pressures 10psi-70psi).