ABS TPMS

[jim.gm4dhj]

why don't car makers make more ABS TPMS systems rather than having four stupid UHF transmitters with batteries flying around in circles?....stupid

[Michael Chare]

There are no pressure sensors in the wheels of my car. The car just monitors the rotations and reports a fault on the dashboard if one of the tyres rotates differently because it has a low pressure. Unfortunately I get many false warnings.

[Colin Bignell]

The only time I get false warnings is if I forget to reset the system after having a new tyre fitted. The problem I once found was that, because it only samples at intervals, a rapid leak, caused by a large stone in the tread, wasn't indicated until after it had caused enough damage for the tyre to be beyond repair.

[mm0fmf]

ABS based systems take much longer to spot changes than the wireless ones. Hence the reason for the wireless ones.

Proper cars offer both with the option to code off the TPMS version and just use ABS system. Typically done when you swap your summer wheels and tyres for your winter wheels and tyres and don't have TPMS in the winter set.

[Brian Gaff]

A friend of mine had a bmw mini that was always complaining of one or more tyre pressure problems, on checking nothing was ever wrong with any of them. Are you saying then that they merely work on rotation or something with a transmitter? Seems somewhat crude to me. Sounds like a job for a bit of cardboard over the dash display. I'm sure you would notice a real flat!

As for brakes etc, there are so many reasons why the braking will vary, I'm surprised they can be very accurate. Brian

[Rod Speed]

Much more difficult to design and don't give a direct tire pressure measurement.

[jim.gm4dhj]

good ....ABS type then...

[jim.gm4dhj]

useless TPMS

[Rod Speed]

Yep.

Not with an ABS TPMS.

Its actually very sophisticated and hard to do well.

You don't with my Hyundia Getz. In spades with under inflation.

[jim.gm4dhj]

but they don't cost ypu a fortune either....

[jim.gm4dhj]

worst of both worlds then

[jim.gm4dhj]

and over complicated

[mm0fmf]

Brian,

The TPMS is a small pressure sensor and radio transmitter mounted inside the wheel. A receiver is in each wheel well. The TPMS has a Lithium cell (such as a CR2032) inside. They are sealed for life and typically that is 4-10years. After that you install new ones. Prices vary but they start around £25 each. Of course premium brand main dealers may ask a lot, lot more for the same item. Some TPMS units need configuring to the car, other cars are self-learning when you swap wheels.

There is a centrifugal switch so the unit is only powered when the car is moving fast enough. The inbuilt computer in the sensor measures the pressure and sends the data over the radio then goes to sleep for some time, wakes up and then measures the pressure and send it again and sleeps. My car shows pressures in the tyres to 1/10th Bar accuracy. I can see my nearside front tyre looses pressure faster than the other 3.

All new cars have TPMS now but if you have run flat tyres it's essential. They can get punctured and run flat and the handling may not change enough for you to immediately notice. Or ever notice if you are clueless and mechanically inept. Whilst you can drive on them when flat you can't drive that far or at speed so you need something to tell you that you have a flat. It may not quickly respond to a blowout condition, it will warn you that a tyre is deflating so you can stop and do something. But not fit the non-existent spare tyre!

Warning lights on a dashboard are a MOT fail nowadays and as they're all integrated LCD monstrosities it's not like you can remove the bulb any more .

[jim.gm4dhj]

fight against it...buy three bangers like me