TPMS Explained
What is TPMS (in a nut shell):
A Tyre Pressure Monitoring System (TPMS) is a safety feature that continually monitors a vehicle's tyres and alerts the driver if the tyre pressure changes outside of tolerance. From November 2014, all newly manufactured vehicles use a TPMS system as part of the new legal requirement, however, the technology has been present since 2000 in many vehicles. A pressure loss warning light on the vehicle's dashboard will cause an MOT failure.
Do I need to worry about it?
If your vehicle is fitted with TPMS then it is imperative that this feature operates correctly on the vehicle, not only as from a safety perspective but it will deem your vehicle as not road worthy if not in operation.
There are 2 ways in which TPMS operates (dependant on your vehicle), INDIRECT or DIRECT:
INDIRECT Systems:
This system operates by external sensors from the wheel assembly (usually from the ABS) and the sensors are looking for a diameter change in the tyre and comparing relative wheel speeds. This will occur when pressure is lost, so the sensor alerts the driver via the onboard computer that there is a pressure loss. No tyre pressure reading is provided and the driver isn't informed which tyre has lost pressure.
For this system NO ADDITIONAL PARTS ARE REQUIRED, which saves you time and money! But you will need to reset the stored tyre pressures on the onboard computer once you are happy with the tyre pressures.
DIRECT Systems:
This system operates by having a sensor attached to each tyre valve (concealed within the tyre), which detects the pressure of each tyre. This is transmitted to the onboard computer and the driver is often able to see the exact tyre pressure in each tyre, and the driver will be alerted if there is a drop in pressure outside of tolerance. Although this type of system is more expensive it will provide a much more accurate indication on whether the tyre has lost pressure.
If your vehicle has this system then there are several ways in which you can approach this:
- Purchase new TPMS sensors from us - available when adding Alloy Wheels to the basket or here. They will be pre-programmed for the vehicle to the correct frequency, but you will need to apply the relearn procedure for which additional information will be provided, or can be followed in your vehicle handbook. Some vehicles need additional programming which can be performed at a tyre centre / vehicle manufacturer dealership local to you. If ordering tyres we will pre-fit the sensors for you into the wheels as part of the tyre fitting process.
- Transfer your existing sensors onto the new wheels, but this will incur additional costs by a tyre centre as they will need to remove your existing tyres, remove the sensors, refit sensors to the new wheels and refit the tyres. If ordering tyres from us please let us know in advance if you wish to do this, as we can then supply the tyres unmounted to the wheels for you.
- You can purchase your own new sensors and send them into us, we will fit them free of charge for you when we fit your tyres here. However, we can accept no liability if the sensors do not function correctly when mounted to vehicle/or are incorrectly supplied to us in the first instance.
How do I know if my vehicle is DIRECT or INDIRECT?
Unfortunately there isn't a system that we can lookup this up for you, however you can get an indication of which system you need by a simple check on the vehicle:
- Firstly check the dashboard and see if you can see the exact tyre pressures like shown:
If not then:
- Deflate the air in one tyre (keep the vehicle stationary)
- Check the dashboard for a warning message
- Check if the warning message tells you the exact corner where the loss in pressure has occured
- Inflate the tyre back to the correct pressure before driving.
If either of the above checks are true then you have a DIRECT system. If they are both false then it is a strong indication that you have an INDIRECT system.
Still not sure what your vehicle has?
If you are unsure whether you have an INDIRECT or DIRECT system then you can always contact the vehicle manufacturer (via your local dealership) and they should be able to tell you by checking the vehicle registration number or VIN number.
Relearn Procedure:
When fitting new TPMS to a vehicle, a relearn procedure needs to be applied. This is the process of registering the IDs of the sensors to the vehicle's ECU so that they can be recognised and read correctly.
Most vehicles have an automatic relearn procedure which doesn’t require any interaction from the fitter/driver. However there are vehicles that have a more complex relearn procedure or require an OBDII relearn which consists of scanning the sensor with a special tool and uploading the sensor ID to the vehicle’s ECU (OBDII relearn).
This can sound daunting, but is a simple procedure and very common now-a-days. The relearn procedure is normally mentioned in your vehicle’s handbook, but we can send you the instructions for your vehicle if required.
In the event that an OBDII relearn is required, we will endeavour to alert you so that it can be carried out once the wheels are on the vehicle (which a local garage/tyre centre will be able to do for you).
If the sensors aren’t recognised by the vehicle, this is 99% of the time due to the relearn procedure not being carried out correctly.
