Tpms

[Tannaton]

There were some really good early systems that would show you the actual tyre pressure on the screen - my 13-plate VW Passat had that and it was great, you could see the pressures increase on fast corners.

Then the EU mandated TPMS in all new cars and I believe at certain times it had to be one of a specific number of approved systems and that precluded some manufacturers that had gone their own way.

The most common EU approved system uses the ABS wheel speed sensors to detect very small changes in rotational speed of the wheel relative to the other three, such changes would be caused by loss of pressure and hence the wheel shrinks slightly. This is the system used by Volvo and the majority of car manufacturers. It requires no sensors in the wheels.

Compared to live TPMS monitoring - it's absolutely crap. It will tell you over a period of several miles at speed if you have a slow deflation, it will not tell you that you've just run over a nail and they tyre has gone flat in 100 yards on the motorway. It will not tell you when you start the car in the morning that your tyre has gone flat overnight.

I'm not sure what's happened since but seemingly Volvo's standard system is the crap one which isn't good for such a safety focused manufacturer.

I might not be 100% accurate with the above but its what I have in my head after reading quite a bit about it.

[Bashy]

Originally Posted by Tannaton

The most common EU approved system uses the ABS wheel speed sensors to detect very small changes in rotational speed of the wheel relative to the other three, such changes would be caused by loss of pressure and hence the wheel shrinks slightly. This is the system used by Volvo and the majority of car manufacturers. It requires no sensors in the wheels.

Its a shame re that system, although the changes cant be that small, I mean, a tyre runs a fair bit hotter once its moving and that expands changing the pressure within, I can see this actually happen on the Renault system, my last 04 Laguna, had one failed sensor, I think that's a pretty good run at 15 years. Winter and summer would have an increase and decrease in air, so if the system registers "very small" changes, at least with the Renault system, you can see whats changed and can make an informed decision, where as you cant really do that with a system that just gives you a puncture icon. To be honest, I think I would save my money if its an option.