CosmoMonkey

Hi, a couple weeks ago I picked up a 2004 RX8 Grand Touring for a nice price and put some money into getting it going again (battery, coils, wires, starter, set of keys, and a warranty replacement engine). Anyway, after getting it back from the Mazda dealer this afternoon I put new tires on it at my work and proceeded home. The TPMS light started flashing and I'm trying to figure out if the 2004 8 is supposed to have stem mounted TPMS sensors or is tire pressure calculated thru the abs speed sensor? It had rubber valve stems in it and I replaced them with fresh ones. Thanks for any help!

EDZRIDE

iTrader: (1)

You need to install a set of sensors; the "stem type".

REDRX3RX8

My new 07 GT had some after market Enkei GF-1's installed without the sensors so my TPMS never worked from day one.

I'm not even sure they would work at the 42# cold pressure I run on the way to track my car, and the light is good to tell me the tires are warm. Ha!

Everything in life is about perception; learn to change it for happiness.

CosmoMonkey

Bummer! I wonder why the former owner yanked them out.

jewagr007

iTrader: (1)

Could be a number of reasons but here is the 2 I have ran across...

1) They will not fit on all Aftermarket Wheels so if the wheels have been changed this could be the reason.

2) If the previous owner ever brought the car to a "discount" tire shop to get tiers, they most likely broke them either taking off the old tires or installing the new ones (most places like this don't even know what a TPMS is let alone look for it to not damage it) and when the tires were swapped again the previos owner didn't want to pony up the dough to change them out.

godesshunter

This may or may not help you but being at a tire shop I hear this every day. Check out this link. It prety much tells you everything you need to know about TPMS

http://www.tireindustry.org/default....&LangType=1033

JohnnyG

What's the easist way to test TPMS? I recently bought a 2007 GT and it has "factory" Mazdaspeed wheels (was a Mazda promotion when it was new). No doubt these were dealer installed, so you'd figure they'd move the TPMS over, but when I picked up the car and checked the tire pressure, one was down about 10 PSI versus the others and no light. No doubt the dealer could have disabled the system, but not sure if it was necessary due to the wheels, or it was a cop out of some sort.

xexok

As I understand it the light *should* come on if all the tires are very low or even if one tire is far enough out of sync pressure-wise with the others. Not sure when it comes on exactly but I believe it is around 25 or 26 psi, if a tire goes that low the light should come on.

godesshunter

Check the dashboard light when you turn the key on first thing. look for the TPMS logo. it is a "U" shape with a "!" in the middle. that light will come on for 2-3 seconds to test the system then go out if there is no fault. Also you can look at the valve stem on the wheel. If it looks like a Grey metal bolt then it is a TPMS valve, if it is just a flexable rubber valve then it is not TPMS.

2007 is the cutoff for all manufactures to have TPMS. It is now a federal requirement. But the mandate didn't go into affect till about half way through 2007. Lots of early production 2007 cars dont have it.

The mazda dealer cannot remove/disable the system legally. Its a federally mandated safety requirement much like seat belts and airbags.

godesshunter

That type if TPMS works off of a signal sent from the ABS tone ring. Mazda doesn't use that type. Mazda uses radio signals from the bolt in valves.

rx2kill

Is it still the stock rims? where did you get the tires done?

JohnnyG

In 2007, Mazda Canada has a promotion for RX-8s that included Mazdaspeed Wheels, Mazdaspeed intake, and a few other appearance items. I'd assume that the dealer was installing these items rather than coming from the factory configured this way. The car has less than 30,000 Miles on it and the tires are original. The previous owner bought and traded it at the same dealer, who I then bought it from, so I guess if it doesn't work, I have a legitimate beef with the dealer.

These are the wheels:

xexok

https://www.rx8club.com/series-ii-interior-audio-electronics-167/rxduino-development-chat-218257/page4/

So Mazda chose to only say when all 4 tires are low pressure? Cant RF still communicate that a tire is low? By "far enough out of sync" I am assuming someone has around 32LBs of air in their tires and if one dropped say 5 or 6 LBs it SHOULD go off, if it does not then this system is useless lol. Does it only detect when a wheel has gone down below 25/26 psi?

ken-x8

The TPMS gets separate pressure data (actual psi) from each tire, and will light up if one is out of range. It's an absolute range, not relative between tires. I don't remember the values, but I'm sure they've been posted somewhere on this site.

RX-8's TPMS does not know which tire is at which corner, so when the light comes on you need to get your tire gauge out and find which one. Not a big task.

Ken

xexok

Yea, I have never had just a single tire need air yet so thats fine lol. When the light has come on once before it was a cold day out here and they were all a bit low, around 25/26 psi. I wish it could tell based on each tires air weight and not a set number that would be such a better system.

ken-x8

Here's the TPMS psi range. Secondary source, but one I believe:

https://www.rx8club.com/rx-8-discussion-3/tpms-173414/#12

Since the recommended tire pressure is 32 psi, and the main problem with tire pressure is it getting too low, I think they've got the right system.

Ken

godesshunter

Having the TPMS system in place is not designed to be a convenience to the owner. That is only a secondary byproduct of the main function. The main function is for safety reasons. When you are doing 150 mph in the highway (and this stands for any manufacturer) and your tire blows out because you had 10 psi in it and you side swipe a bus load of school children you cannot go back and sue Mazda for putting "crappy " tires on your car.

The same holds true for the tire placard info sticker in the drivers door jamb. As with the school bus scenario, if they find you had the cheapest dirt floor Chinese H rated tires money could buy on the car, you cant play the "I didn't know" card.

This all goes back to the Ford Explorer/ Firestone tire thing that happened about 10 years back. Im sure you all remember that? Ford was too cheap to put on good quality tires on them. And Firestone gave the lowest bid to sell Ford an inferior tire for big sales numbers. The end result, hundreds of people died.

The Firestone Wilderness AT (that specific recall tire) was a good tire. However with an initial low temperature threshold rating of a "C" and negligent owners letting their tire pressures drop down the 20s and sometimes teens led to disaster on extended interstate runs when the tires would heat up.

Another little know fact about that whole mess is that there are still hundreds if not thousands of those tires still on the road. When Ford and Firestone issued the nation-wide recall and replaced everyone's tires that had those Explorers They neglected to replace the full size spare under the truck. For a long time people were collecting them and making full sets out of them to run for normal everyday use. Luckily most of them are now gone due to the "cash for clunkers" program. Ford Explorers were I think among the top 5 of clunkers traded in.

Next time you are bored look in your owners manual index for "tire info". Next to the radio-navigation, its the largest section in the manual dedicated to only one topic. It explains tire size, speed rating, load index,TPMS and all the dangers and warning to go along with it. Auto makers are saving their own asses and putting tire problems more on the blame of owners. Their argiment?: We told you so.
The tire industry and all the legalitys that go along with it are a much bigger deal than most people think.

Regardless of how much money you have dumped into your car or how safe it is with airbags and abs and lane departure and doze-off warnings and all the like, only one thing on the whole car is touching the road.

A car is only as good as the tires its on.

godesshunter

Of all 13 posts in that thread only 2 were correct and they were from jedi54. The rest is just ignorance

godesshunter

I'm not sure what Mazda's magic # is. Every manufacturer is different. Its usually about 10-12 psi. The tolerance is pretty wide though on purpose. They have to consider a national system that will work. They have to consider changes in climate and altitude that will have vast affect on internal tire pressure depending on where you are from.

If the tolerances are too tight that will be a huge pain for all that are not in the same altitude and climate of the location where the system was calibrated.

godesshunter

On a side note I run my pressure at 40 psi.I check my air religiously once a week every Saturday after work. And just today I boosted it up to 51 psi for winter storage. The whole way home the TPMS light did not come on. I don't know the exact psi recommended for my car but I think its 32.

ken-x8

Are you saying the numbers Swoope gave are wrong?

BTW - on the Explorer/Firestone thing... I would not consider any tire with a C heat rating to be a good tire. Also, the tire safety obsession did not begin with the Explorer problem. Remember Firestone 500s back in the 70s? Fatal accidents, congressional hearings, massive recall. The initial wrecks nearly scuttled the transition to steel belted radials, until everyone realized it was just the Firestones that were shredding.

Ken

ken-x8

If it's an RX-8, recommended is 32. All that tire safety info in the owner's manual and there are still people who aren't sure about the number.

Since 51 did not trigger the TPMS light, it looks like the 52 Swoope cited is correct.

With those high pressures, make sure you're not exceeding the maximum pressure marked on the sidewall. For the Bridgestone all seasons I've got on my 8, that's 40 psi. YTMV. Usually that upper limit is there for the benefit of the tire installer, who'll use extra pressure to seat the bead.

Ken

Mazurfer

Jesus...........I can't believe this is still being discussed.
The numbers are not exact, on either end, but both Swoop and I have seen just over 50.......however we would never run there.
I run about 33-34lbs as a rule.


Actually, I'm suprised nobody told him to check that nobody covered up the TPMS light with black electric tape!



CAUSES OF A TPMS MIL & WARNING BUZZER
• Aftermarket wheels or factory replacement wheels installed without wheel sensors
• Tire pressures were adjusted with tires hot, light comes on when vehicle is cold. (Tire pressures must always
be adjusted cold)
• Low air pressure in any or all wheels {below 179.26 kpa (26 PSI)}
• High air pressure in any or all wheels {above 337.84 kpa (49 PSI)}
• Spare tire installed on vehicle
• Instant Mobility System repair agent or fix-a-flat was used and is clogging a wheel unit
NOTE: The TPMS system will turn the warning lamp off after the vehicle is driven over 25 KM/h (16 MPH).
Example: If you correct tire pressure after repairing a flat tire, or reset tire pressure to the proper range,
(such as at PDI to correct high shipping tire pressures), the TPMS warning light will stay illuminated
until the vehicle is driven over 25 KM/h (16 MPH).



If you care, I attached the TSB that contains the above and other info.

godesshunter

No, I will not say Swoope's numbers are bad. I personally dont know. Sounds good to me. I think I dismissed that post at first glance due to the beers smiley face thing.

Perhaps I used the term "good" too loosely when refering to a C rated tire but that doesn't make it bad either. I just think the tire was used way beyond it manufactured intention. That tire is fine for a pickup with weekend use and limited highway travel. It should have never made its way onto family passenger vehicles. Ford should have known better.

As far as the Firestone 500 I'm sorry but that is beyond my years. I've been in the tire business for just the past 10 years. I cannot speak for what happened before my time.

godesshunter

Yes it is an rx8 and the Potenzas on mine have a max rating of 51. Hence my top out pressure of 51