I read it somewhere that the RX-8 has a tire pressure inducator on dash. Is this true ? I can't seems to find this listed in the Canada RX-8 dealer spec.

well i can't find the picture right now but there is an indicator for the tire pressure monitoring system on the dash. it's in the left gauge pod below the shift light. i think it's yellow and it looks like a flat tire. i know that pic is on the forum somewhere.......

How do these tire pressure indicators work exactly?

Does it measure low pressure with the ABS sensors on each wheel or something? Flatter tire turns more frequently than the others due to a smaller diameter and registers the difference that way??

I've always wondered about how this works, and I can't think of any other practical way that this could be done (mechanically/electrically).

91Vert,

There are two ways to measure, direct and indirect.

The indirect is through ABS system as you describe. They are able to count the number of revolutions of the wheel and when a wheel starts to rotate significantly faster than the other wheels then the computer assumes the wheel is going flat. This system requires only a little more computer code and a dash warning light to work properly, but it takes time to work properly so it isn't as fast as the direct method.

The direct way uses long life wireless air-pressure sensors mounted in the tires to measure pressure. The pressure signal is then transmitted to the reciever periodically. The battery life is about 10 years on the direct pressure measurement systems.

Now if you were asking what type the RX-8 actually uses, I don't know. My guess is the indirect way because it is cheaper. Also manufacturers usually like to brag if they are actually using real sensors to do inflation pressure monitoring. Since few (if any) have heard anything from Mazda about tire pressure monitoring, I would assume it is the least invasion method which is the indirect method.

-Mr. Wigggles

Zoom44,

I don't see any clear low tire pressure warning light in this picture:

http://www.mazdausa.com/MusaWeb/rx8/images/gallery/rx8_images_49.jpg

Other than the yellowish-green circular symbol in the left guage cluster. I think all of the dummy lights are on, but they might have added more since this pic was taken.

-Mr. Wigggles

Thanks for the explanation Wigggles, I always wondered how they read the pressure without actual in-tire sensors. Here's a shot of the gauges during startup, in the front-lit blue stage (before the white backlighting of the dials comes on). Sorry for the fuzziness, it's from video.

wiggles i couldn't find the pic i am talking about i founnd that pic you posted and your right its not in it. i dont see it in gamera's pic either but i knowit's in one of the dash pics somewhere on this board it might be the one in gamera's just below the shift light butsince it's just starting up it isn't indicating flat. the pic i'm talking about shows a yellow U in about the same place.


ohoohoh here it is in an image from rotarynews.com. it's right above the shift light

http://images.rotarynews.com/images/Detroit2003_1/mvc01350.jpg

Wait -- so it doesn't indicate what the tire pressure is for each tire, it just shows that one of the tires is low??? So, then you need to check all four tires anyway to see which tire it is???

So, this is just a "check your tires, you idiot" light???

I want to know what the yellow "steering wheel with an exclamation point" light is, above and to the left of the tire indicator. Maybe it's a "You're driving like an idiot" light!

Originally posted by jonalan
Wait -- so it doesn't indicate what the tire pressure is for each tire, it just shows that one of the tires is low??? So, then you need to check all four tires anyway to see which tire it is???

So, this is just a "check your tires, you idiot" light???

yup:D

Maybe the little Stering wheel light is the stablilty control :confused:

Originally posted by RotorGeek
Maybe the little Stering wheel light is the stablilty controlThat would make sense. Give that man a kewpie doll!

WOOHOO

A kewpie doll. I.ve allways wanted one:D

I have a C5 Corvette that gives a digital readout of the exact tire pressure in each tire at any given time. It is a very nice feature that I use more often than I thought I would. It would be nice to see this type of tire pressure monitoring on the RX-8 but I would suspect that it is much more expensive than the warning light. I do think the warning light is sufficient and would not want the added cost for the Corvette type set up as nice as it is. As with the Corvette it is nice to have this feature when there is no spare on board.

Originally posted by KCROTOR
I have a C5 Corvette that gives a digital readout of the exact tire pressure in each tire at any given time. It is a very nice feature that I use more often than I thought I would. It would be nice to see this type of tire pressure monitoring on the RX-8 but I would suspect that it is much more expensive than the warning light. I do think the warning light is sufficient and would not want the added cost for the Corvette type set up as nice as it is. As with the Corvette it is nice to have this feature when there is no spare on board.

The Corvette uses the direct method I mentioned earlier. So it is able to give very accurate results for all four tires due to the sensor mounted in each of the four wheels.

One of the nice things about the indirect method is that since there are no sensors in the wheels, the sensors don't have to be remounted on aftermarket wheels if someone wants to go that route.

Zoom44,

Thanks for digging up that picture for us.

-Mr. Wigggles

happy to help:)

NOTE : A recently passed federal law* states that all cars will have to come with some sort of onboard sensor for tire pressure. Real-time displays are just additional toys manufactuers get to develop and install as gimmicks and as value-added features.

heh you can thank Ford and Firestone for that little sensor on the dash :)



*TREAD (Transportation Recall Enforcement Accountability and Documentation) Act passed into law in November 2000 to enhance tire safety and prevent future injuries and fatalities. The law requires that, from November 2003, newly registered light vehicles in the U.S. must be equipped with tire pressure monitoring devices.

Originally posted by DrKillJoY
heh you can thank Ford and Firestone for that little sensor on the dash :)
[...]
The law requires that, from November 2003, newly registered light vehicles in the U.S. must be equipped with tire pressure monitoring devices. The vehicles that Ford and Firestone had issues with, are hardly what I'd call light!

Originally posted by Gamera
Thanks for the explanation Wigggles, I always wondered how they read the pressure without actual in-tire sensors. Here's a shot of the gauges during startup, in the front-lit blue stage (before the white backlighting of the dials comes on). Sorry for the fuzziness, it's from video.

Video??? What video??? Is it on the forum somewhere??? I gotta see it!!! Please tell me where it is!!! Must...see...video....

Originally posted by khoney

Video??? What video??? Is it on the forum somewhere??? I gotta see it!!! Please tell me where it is!!! Must...see...video....
From the "Intro" video of Best Motoring 03-2003 (the links are live again). The original post is here:
http://www.rx8forum.com/showthread.php?s=&postid=30121#post30121

Or try Cylo's mirror:
http://www.rx8forum.com/showthread.php?s=&threadid=2729

:biggrin:

yeah, I know what you mean...I think "light" refers to any personal type transportation. (ie; not 18 wheelers, cargo trucks etc.)



Originally posted by eccles
The vehicles that Ford and Firestone had issues with, are hardly what I'd call light!