First car with TPMS.

 

Traditionally you have a new valve fitted when you change the tyre. How does it work with TPMS. 

 

Does the sensor have a lifespan? Is there any servicing of the sensor / valve needed? How much extra are tyre changes likely to cost?

There aren't any sensors. It works by magic using the wheel speed sensors (ABS).

I believe it works on the principal that if a tyre deflates then its circumference will decrease slightly, which means it will rotate more than the other tyres when the car is moving. This difference will be detected and displayed as a warning  message.

 

When you check/top up your tyre pressures (all at the same time) you should also recalibrate the tyre monitoring system (easy job via the infotainment display) to set the basis for future comparisons.

34 minutes ago, Wino said:

There aren't any sensors. It works by magic using the wheel speed sensors (ABS).

 

You learn something new every day. I guess this is why it reports loss of pressure, rather than an actual pressure reading.

 

Any idea how accurate it is? What pressure drop is typically needed for a warning? If it works, makes you wonder why others are using tpms sensors?

 

 

You'll find many cars use this system probably.  Direct tpms has got to be far more expensive.

4 hours ago, Jase_31 said:

Any idea how accurate it is? What pressure drop is typically needed for a warning? If it works, makes you wonder why others are using tpms sensors?

 

 

I've found that on my Golf (same basic system) it takes around a 10-20% difference to flag up as a warning. 

 

The better (and more expensive) TPMS  displays exact pressure values for each wheel so you need to physically check and get your hands dirty rather less :-)

4 hours ago, MarkyG82 said:

Direct tpms has got to be far more expensive.

Latest set costed me just 4 euros, previous 53,

but yes OEM set will cost several hundreds

 

stock Indirect system gives false or too late warnings

 

the indirect TPMS version is good and accurate.  it uses the ABS sensors to determine "tyre pressure loss".

 

the direct TPMS  uses a sensor valve in each tyre to give u actual tyre pressure readings.  the battery in the valve sensors have a 10 yr lifespan.

i recently upgraded mine from the indirect to direct version, as per the link posted above by @MartiniB.

 

standard/default Indirect Tyre Pressure Loss Indicator (Indirect TPMS) vs Direct Tyre Pressure Monitoring System (TPMS)

 

11 hours ago, MarkyG82 said:

Direct tpms has got to be far more expensive.

 

not really. 

it cost me $200 to retrofit the direct tpms (OEM version) to my Superb.

u can get much much cheaper direct tpms kits that use either a smartphone app, or a small unit that sits on ur dashboard, showing the readings.  @MartiniB has got this version, and has provided links for it.

Edited 20 January, 20215 yr by JR RS

17 hours ago, Jase_31 said:

 

You learn something new every day. I guess this is why it reports loss of pressure, rather than an actual pressure reading.

 

Any idea how accurate it is? What pressure drop is typically needed for a warning? If it works, makes you wonder why others are using tpms sensors?

 

 

 

The designed function (legal requirement) isn't to remove a maintenance need, but to give a heads-up about an emergent, dangerous tyre deflation situation. As such it doesn't need to have accuracy with respect to actual tyre pressure. The wheel size and tyre size/width/aspect ratio/load rating/temperature will all have impacts on the relationship between rolling radius and tyre pressure, so the pressure change required to give a warning is fairly irrelevant.

 

As with a lot of these mandated safety systems, over-reliance on them ("no need to check tyre pressures any more, the car looks after that for me") will be foolish.

 

My wife’s yoke has in wheel sensors. Genuine sensors were £20 each, as I bought a full set when I was fitting her winter wheels and tyres. 

17 hours ago, JR RS said:

not really. 

it cost me $200 to retrofit the direct tpms (OEM version) to my Superb.

 

My statement was intended towards the manufacturers where indirect is mostly a bit of added coding. Extra hardware in the wheels and receiver in the car system has got to be more expensive at manufacture? Yes I know that adding features in the factory is far cheaper than retrofit bit with the numbers involved the indirect system is a better solution for the manufacturer.