Intro4u2u

These handy pressure valve caps claim to let you know when your rubber is under-inflated. We put six sets to the test to see which ones can be relied on…
Did you know that if your tyres are under-inflated by 10 per cent, their life will be cut by the same amount? Yet most drivers don’t check their pressures often enough – so products that give at-a-glance warnings are booming.

Usually, these replace the valve cap, and alert you to any psi loss via coloured inserts; green means everything is OK, while red (and sometimes yellow before it) indicates the pressure has dropped. But some of the kits are based on conventional gauges.

We set out to see if such devices really can help you take better care of your tyres.

The test

Using a wheel and tyre with three valves, we checked the cap alerts while monitoring the slowly released pressure with a digital gauge.

Ideally, we wanted to be able to spot even a small pressure loss. We also factored in price and convenience, with marks lost if you had to do anything more than simply look.

Most products are sold on the Internet, so allow for delivery costs if buying online.

Verdict: Regular pressure gauge checks are still the best option, as the valve caps were slow to react to air loss. As a failsafe, the Pressure Guard is our pick of the bunch. The Auto Unique TPMS Remote trailed it only on price.

1. Pressure Guard
2. Auto Unique TPMS Remote
3. Bike It Pressure Alert Valve Caps

EMAIL TO A FRIEND               PRINT THIS

1. Pressure Guard
Price: £12.50 per four Automatic: Yes

Black plastic valve caps featured small, clear bubbles at their ends and, unlike rivals, weren’t preset, being suitable for tyres between 20psi and 42psi. With the tyre correctly inflated, the cap was fitted and the green outer segments appeared. As pressure was released, the central red wedge was exposed, and it started to show with a loss of 4psi. Good price helped it come out on top.

2. Auto Unique TPMS Remote
Price: £45 (est) Automatic: No

Tested here as a prototype, this device will be smaller when it goes on sale in February. The handheld display works as a normal gauge. But once the correct pressure has been entered, when you hold it close to one of the caps– each has a battery and four LEDs – the lights flash according to the psi. Gadgety and pricey, but does what it says on the tin.

3. Bike It Pressure Alert Caps
Price: £13.96 (£3.49 each) Automatic: Yes

It was close between these and the Aircheckers in the test, apart from their pressure limits. Confusingly, the 28psi cap had to be selected for 29-30psi, and 30psi for 32-34psi. The caps are from a bike supplier, and are sold separately. But our 28psi samples indicated only a little yellow at 26psi, and red didn’t show until 22psi. Not what you need on two or four wheels.

4. Aircheckers
Price: £17.95 per four Automatic: Yes

Smart-looking in a chrome-effect finish, the Airchecker had individual preset limits in 2psi increments from 26-42psi – more than enough for car use. But with a loss of 4psi, the yellow segment was barely visible. Even at 8psi, it was hard to make out the red section; this should have been easy to see, even from a distance. Not that effective, and pricey compared with the similar Bike It.

5. Quik-Chek Press. Monitors
Price: £17.95 per four Automatic: Yes

Better value than the KeyChain, but the permanent-fit Quik-Chek caps would be too bulky for some wheels. The sprung end had to be pushed in for a reading, which varied according to how hard it was pressed. We couldn’t easily see the red section until 25psi; a worry, as the green section was around 30-34psi. Large, awkward and too tricky to read.

6. Quik-Chek KeyChain
Price: £4.64 each Automatic: No

Although offered ‘free’ online, there was still a carriage charge for this poor man’s pressure gauge. It’s big and cumbersome, making access tricky on some alloy designs, and has to be unclipped from its keyring before use. To get a reading, you remove the valve cap and replace it with the Quik-Chek, so a gauge would be less hassle. Worse still, the alerts were worryingly slow.