"Harry Krause" wrote in message
...
Out of curiosity, might someone who actually knows share how those "tire
pressure low" indicators work?

I don't mean the ones you put on your tire valves; I mean the ones that
come stock on some new vehicles, and set off a warning light on the dash
when a tire is low.

Oh, and I'm thinking of getting a set of valve pressure indicators for my
boat trailer tires. Any recommendations?

Thanks!



Most are mini transmitter devices. My wife's car still has the blue
stickers on the rims with the transmitting frequency printed on them. (BMW
750)

However, not all are. Are you ready for this? Here's how it's done on my
BMW M5:

You, or the dealer inflates the tires to the proper pressure.

You enable the flat tire monitor (on BMW's this is done through a computer
interface called "I-Drive". This calibrates the system.

As you drive around, a sensor on each wheel records the wheel rotation and
compares it to the other three wheels. Each sensor compares to the other
sensors, in other words. If one tire starts going flat, it's number of
rotations per unit distance will be different than the other three wheels.
If this difference goes out of a predetermined window (allows for turns,
etc.) the flat tire alarm will notify the driver.

I had to read this three times in the manual before I'd believe it. German
engineers have a reputation for getting carried away, but this is
ridiculous.

RCE

On Thu, 30 Mar 2006 20:19:59 -0500, "RCE" wrote:

As you drive around, a sensor on each wheel records the wheel rotation and
compares it to the other three wheels. Each sensor compares to the other
sensors, in other words. If one tire starts going flat, it's number of
rotations per unit distance will be different than the other three wheels.
If this difference goes out of a predetermined window (allows for turns,
etc.) the flat tire alarm will notify the driver.

I had to read this three times in the manual before I'd believe it. German
engineers have a reputation for getting carried away, but this is
ridiculous.

How did we ever get by without micro processors ?

Most are mini transmitter devices. My wife's car still has the blue
stickers on the rims with the transmitting frequency printed on them. (BMW
750)

However, not all are. Are you ready for this? Here's how it's done on my
BMW M5:

You, or the dealer inflates the tires to the proper pressure.

You enable the flat tire monitor (on BMW's this is done through a computer
interface called "I-Drive". This calibrates the system.

As you drive around, a sensor on each wheel records the wheel rotation and
compares it to the other three wheels. Each sensor compares to the other
sensors, in other words. If one tire starts going flat, it's number of
rotations per unit distance will be different than the other three wheels.
If this difference goes out of a predetermined window (allows for turns,
etc.) the flat tire alarm will notify the driver.

I had to read this three times in the manual before I'd believe it.
German engineers have a reputation for getting carried away, but this is
ridiculous.


That seems really odd. On my Infiniti, there is no calibration to proper
pressure and then a warning if you fall outside the accepted range of the
calibrated pressure. The Infiniti's system seems a bit more
straightforward. By switching to one of the ancillary screens on the LCD
nav display, I simply get a real-time digital readout of actual tire
pressure in psi of all four wheels on the ground. As the tires warm up, I
can see the pressure increase correspondingly. The left front may read 34
psi while the right rear may read 33 psi, etc. If any tires falls below an
absolute pressure 29 psi, a warning screen will automatically pop up on the
nav display. Seems a lot more simple and intuitive than any other system
I've seen described in this thread.

On Fri, 31 Mar 2006 11:27:54 GMT, Shortwave Sportfishing
wrote:

How did we ever get by without micro processors ?

It was called common sense.

I knew it must have been something in short supply.

"Wayne.B" wrote in message
...
On Fri, 31 Mar 2006 11:27:54 GMT, Shortwave Sportfishing
wrote:

How did we ever get by without micro processors ?

It was called common sense.

I knew it must have been something in short supply.


LOL!!


RCE (back and safe from a 4050 mile voyage.)

On Fri, 31 Mar 2006 14:27:26 -0500, "RCE" wrote:

RCE (back and safe from a 4050 mile voyage.)

Welcome back.

How does Mrs E like the red truck ?

"Wayne.B" wrote in message
...
On Fri, 31 Mar 2006 14:27:26 -0500, "RCE" wrote:

RCE (back and safe from a 4050 mile voyage.)

Welcome back.

How does Mrs E like the red truck ?


She likes it. Drove it down the street and back and got a kick out of it.
It runs excellent.

RCE