Tyre pressure monitoring systems explained

Nothing deflates the atmosphere of a caravan holiday like an accident while towing, and deflated tyres are the number-one cause of serious caravan accidents. Here's a solution.

What’s the most dangerous component in your car?

The jokers amongst you may say “the Nut that holds the steering wheel!” but that besides, it surely has to be your tyres. These four pieces of rubber are all that keeps us on the road and yet the actual contact patch – the bit that touches the road – is not much bigger than a handprint.

Under-inflated tyres reduce grip and cornering ability, increase braking distances and wear faster and increase fuel consumption. Bridgestone Tyres surveyed 52,000 cars in 15 EU countries and found that 81% had under-inflated tyres. A tyre which is just 6psi under-inflated will wear 30% faster and increase fuel consumption by up to 20%. So it’s costing you money as well as affecting your safety!

We have all seen the vehicle (unfortunately often a caravan) pulled in on the hard shoulder of motorway with a destroyed tyre. A lot of people think that a ‘blow-out’ is something that is sudden and unpredictable and therefore a moment against which you cannot protect yourself.

In virtually every case that is not true, as the blow-out is the end of a sequence of events which starts with something as simple as picking up a nail or screw in your tyre. At that stage, you will be unaware of this. As the tyre starts to deflate there is more friction with the road, the tyre gets hotter, and eventually, the tyre wall collapses with the catastrophic loss of air which we call a blow-out.

All this takes place with almost no clue for the driver and in the case of someone towing a caravan or trailer, absolutely no clue.

How can you protect yourself from tyre problems as you drive?

There is only one way, and that is to fit a tyre pressure monitoring system (TPMS). So important is it to have correct tyre pressures that from 1 November 2014 all new cars sold in the EU must have a Tyre Pressure Monitoring System (TPMS).

But that new law bizarrely does not apply to caravans or trailers or motorhomes. It is bizarre because it is surely caravans and trailers which are most susceptible to tyre problems – there is no way you can have any ‘feel’ for a caravan and what the tyres are doing while you are towing, so problems only become apparent when it is too late.

And don't think that those blow-outs are not a common occurrence as they account for 1/3 of the road-related caravan insurance claims!

TPMS systems use battery-powered sensors on each wheel to collect data every few seconds on both tyre pressures and temperatures and transmit that information to a central receiver which sits in your car. You can easily fit them in a few minutes (just replace your dust caps with the screw-on sensors), and you can switch them quickly between vehicles or tyres.

Units such as the TyrePilot, Nikkai, Tyresure and Garmin systems, can monitor your tyre pressures and temperatures while driving and then warn you if something goes wrong.

Some of these systems require replacement tyre valves, while systems like TyrePilot’s STP1400 use a small sensor that just replaces the dust cap. Cheap systems are available online, but, as in all cases, you get what you pay for, and you should expect to fork out over £100 for a decent system with some worthwhile warranty.

The batteries last about two years and cost just a couple of pounds to replace. The whole system is wireless, so there are no fitting costs or wires trailing inside your car. And as more and more cars have TPMS fitted as standard it makes sense to install this important safety feature on your caravan as well.

Testing the Snooper TyrePilot

We tried out the Snooper TyrePilot STP1400 on a caravan (towed by a Peugeot 308 SW which has a built-in TPMS).

You need to install the sensors with the monitor switched on. The TyrePilot comes with a set of hex nuts and a tool with which to tighten them onto the valves, before you screw on the sensors.

It was quick an easy to fit the sensors (see video below) onto the caravan's tyres. The unit comes with four sensors, which is ideal if you have a win axle van and need all four sensors. Each sensor has a pre-configured location so you can identify which tyre is which on the monitor.


The monitoring unit fits into the 12V cigarette lighter power socket and includes a USB port so you can plug in your smartphone (or other device) at the same time.

Setting up the monitor was easy too, with a clear set of instructions. We set up the parameter for high and low pressure and also a high temperature setting for the alarms. The monitor includes a 'fast leakage' alarm.

The monitor connects to the sensors using BlueTooth and measures pressure up to 87 psi. The LCD display on the monitor is clear and readable. The alarms are audible and visible.

Once driving you can see the caravan tyres warming up (which is normal). Batteries should last up to two years, according to the folks at Snooper. It's simple to replace the batteries and there is a special tool to remove the sensors caps to do access them.

The TyrePilot STP1400 worked really well, and is a well-designed tyre pressure monitor, which is £99.99 (RRP). We think it is a reasonable price to pay for peace of mind when towing your caravan. You can buy them online at Amazon.