Tire upgrade and pressure sensor question

[rudiger]

<div class='quotetop'>QUOTE(David Beale @ Jul 29 2007, 01:23 PM) [snapback]487106[/snapback]</div>

The tire size has no effect on sensor calibration. The tire sensor measures pressure inside the tire, and compares it to the setting you make once in a while when you press the button (after you check and inflate/deflate appropriately).[/b]

I didn't think the TPM measured air pressure at all. My understanding was it simply compared tire rotation between each side of the vehicle. A preset level of deviation between rotation (as when one of the tires had lost air pressure) was what triggered the warning light. This makes a certain amount of sense since atmospheric conditions would cause tire pressure to fluctuate, but it would cause both tires to fluctuate at the same rate and not cause a warning light.

Of course, if correct, it would seem to mean that there would be certain rare instances where a loss of tire pressure would not cause the warning light, say, if someone drove over a tire deflation strip. In such a circumstance, both deflated tires would be rotating at the same rate.

[IsrAmeriPrius]

<div class='quotetop'>QUOTE(rudiger @ Aug 19 2007, 02:26 PM) [snapback]498798[/snapback]</div>

My understanding was it simply compared tire rotation between each side of the vehicle. A preset level of deviation between rotation (as when one of the tires had lost air pressure) was what triggered the warning light.[/b]

That is not the tire pressure monitoring system that Toyota uses for the Prius. The Prius has actual pressure sensors mounted in each wheel which detect deflation and then transmit that information via radio signal.

[postal1]

<div class='quotetop'>QUOTE(IsrAmeriPrius @ Aug 19 2007, 04:51 PM) [snapback]498810[/snapback]</div>

That is not the tire pressure monitoring system that Toyota uses for the Prius. The Prius has actual pressure sensors mounted in each wheel which detect deflation and then transmit that information via radio signal.
[/b]

What ever you do, don't trust the shop mechanics. I did and may have gone for six months with low tire pressure. Never assume that they do what you would do. Check your own tires!

I had my car in three times for low pressure, each time they found a nail or screw. One the fourth time I checked it myself, all four times were around 24 pounds. Once I fixed the tire myself and inflated the tires, no problems for the last two months.

[rudiger]

<div class='quotetop'>QUOTE(IsrAmeriPrius @ Aug 19 2007, 05:51 PM) [snapback]498810[/snapback]</div>

That is not the tire pressure monitoring system that Toyota uses for the Prius. The Prius has actual pressure sensors mounted in each wheel which detect deflation and then transmit that information via radio signal.
[/b]

It was my salesman that told me it was a tire-rotation-based monitoring system so that explains why the information was incorrect.

What other vehicles (Toyota or otherwise) use a system based not on tire pressure but rotation?

[apriusfan]

<div class='quotetop'>QUOTE(rudiger @ Aug 20 2007, 11:49 AM) [snapback]499248[/snapback]</div>

...What other vehicles (Toyota or otherwise) use a system based not on tire pressure but rotation?[/b]

BMW is one of the manufacturers that use the rotational method. There may be others but I have personal knowledge regarding BMW.

[IsrAmeriPrius]

<div class='quotetop'>QUOTE(rudiger @ Aug 20 2007, 11:49 AM) [snapback]499248[/snapback]</div>

What other vehicles (Toyota or otherwise) use a system based not on tire pressure but rotation?[/b]

I do not know about other manufacturers, but according to this post by Galaxee, Toyota switched to direct TPMS for the '06 model year. Your salesman was out of date, as Toyota previously used an indirect rotation based system on some models.

[rudiger]

<div class='quotetop'>QUOTE(IsrAmeriPrius @ Aug 20 2007, 05:01 PM) [snapback]499364[/snapback]</div>

I do not know about other manufacturers, but according to this post by Galaxee, Toyota switched to direct TPMS for the '06 model year. Your salesman was out of date, as Toyota previously used an indirect rotation based system on some models.
[/b]

That's good to know. With the exception of this one somewhat esoteric faux pas, he had an otherwise reasonable grasp of Prius features.