Wife thinks TPMS is a pain but...

So a few months ago, the TPMS light went on and started beeping while my wife was driving and it kind of freaked her out. She later told me about it and I told her what it was. It turns out the tires were a little low so I filled them back up.

Then about a month ago, it went off after I was coming back form the dealer for the 6 month/5K mile service because it seems the tech forgot to reset the TPMS after filling and rotating the tires. I found them about 39psi +/- 2 so I evened them up and reset the TPMS then gave some feedback to the service manager as this is probably something certain techs forget to do often.

Yesterday, the TPMS went off when we were coming back from the store. She asked why it keeps going off and says that its a pain in the @#$. Anyway, I checked the tires today and found a screw in one of them! It was a $5 fix with the rubber plug things from walmart.

So from my perspective, it has worked perfectly and done exactly as it should both times it went off with my wife in the car. Many people forget to fill their tires when they get low unless there is something to remind them (especially if it's the wife that normally drives it). Many people also don't know if there is a nail or screw in a tire until it goes flat and is really noticeable while driving. It seems the CX-5 TPMS has detected both cases for us and I'm so happy that we don't have one of those TPMS with expensive sensors on each wheel.

Buger said:

Many people also don't know if there is a nail or screw in a tire until it goes flat and is really noticeable while driving. It seems the CX-5 TPMS has detected both cases for us and I'm so happy that we don't have one of those TPMS with expensive sensors on each wheel.

Click to expand...

Glad the system is working as intended.

Some people don't like any inconvenience. I've seen tires so low the rims were almost running on the sidewall. Pointed it out to the owner and he seemed like he couldn't be bothered with such a trivial thing.

System is very good, and especially helpful for negligent owners.

CX-SV said:

System is very good, and especially helpful for negligent owners.

Click to expand...

My TPMS light went on yesterday because of the big change in temp the last few day's.
The temp in my area went from 55f. to -5f. in 2 week's.
My winter tire were installed on my steelies, inside at normal temp so when i installed them on my CX5 (3 week's ago) they were ok, a little bit on the low side 32psi.
But it was 55 outside, now it's -5f. so you can probably expect 1 psi drop for each 10 deg farh. drop.
I wasn't negligent i usually check my tire pressure every 2 week's or so. When the light came on i had 28 psi in each tire.
Anyway i adjust the pressure at 35psi, reset the TPMS button and now everything is ok.
I just want to point out that even when your not negligent it can be really helpful.

Exspeedaway said:

I just want to point out that even when your not negligent it can be really helpful.

Click to expand...

Yes that's exactly why I said "system is very good". Negligent owners are more dependent on it, since they perform no other periodic checks between scheduled services.

CX-SV said:

Yes that's exactly why I said "system is very good". Negligent owners are more dependent on it, since they perform no other periodic checks between scheduled services.

Click to expand...

(thumb) ^^

The tpms system works great for what it's meant for. At times its a pain. Usually when I go fishing or hiking, I'm on dirt roads I always get the low tire light on, either because of dirt in the sensor or just the bouncing of the tires. So I have to stop and check the tire pressure. I've learned to always have a tire gage because of this system. At times I can't stop I pray that it's just the tpms and not a low tire.

Good practice for all cars as mentioned above, to always carry a tire pressure gauge.

Ronbo said:

At times its a pain. Usually when I go fishing or hiking, I'm on dirt roads I always get the low tire light on, either because of dirt in the sensor or just the bouncing of the tires. So I have to stop and check the tire pressure. I've learned to always have a tire gage because of this system. At times I can't stop I pray that it's just the tpms and not a low tire.

Click to expand...

I've been using my CX-5 on a lot of USFS back country dirt roads that are a mess this time of year (mud, snow, potholes, rotted slick leaves, etc.) and my TPMS light never comes on. Plenty of dirt and plenty of tire pounding (I don't go slower than necessary for reasonable safety). This is in addition to my numerous trips to the local ski area which is pretty rough.

I would suggest the problem with your TPMS light coming on might go away if you do an ACCURATE TPMS reset. I have not touched my reset since I added 2 psi to my tires a couple of months ago. After 7000 miles, the only time my TPMS light has activated was shortly after I drove the brand new car off the dealers lot. I suspect it did not have an ACCURATE TPMS reset done by the dealer because it has been quiet as a mouse since.

You do have all 4 valve stem caps on? I'm surprised but many motorists seem unaware that the little valve inside the tire stem is not designed to hold air while driving (only long enough to put the valve stem cap on). The way most valves are mounted, the centrifugal force created by a spinning wheel works against the sealing of the stem. And road bumps and dust/dirt compound the problem. So, always use caps that have good seals.

MikeM, you may get a different result with FWD rather than your AWD due to the transmission working to keep all wheels turning at the same speed. Different wheel speeds is what triggers the TPMS.

GAXIBM said:

MikeM, you may get a different result with FWD rather than your AWD due to the transmission working to keep all wheels turning at the same speed. Different wheel speeds is what triggers the TPMS.

Click to expand...

That's possible - I have no experience with the FWD version. It could also be that the tires need to be rotated more frequently. Front tires wear much more quickly on a FWD vehicle.

MikeM. said:

You do have all 4 valve stem caps on? I'm surprised but many motorists seem unaware that the little valve inside the tire stem is not designed to hold air while driving (only long enough to put the valve stem cap on). The way most valves are mounted, the centrifugal force created by a spinning wheel works against the sealing of the stem. And road bumps and dust/dirt compound the problem. So, always use caps that have good seals.

Click to expand...

I'm sorry, what did you just say?

All tire stem valves are spring loaded units, and the cap is only there to keep dirt from wedging the valve open.
Centrifugal force actually acts in the direction of sealing the valve.

BC.

Bladecutter said:

I'm sorry, what did you just say?

All tire stem valves are spring loaded units, and the cap is only there to keep dirt from wedging the valve open.
Centrifugal force actually acts in the direction of sealing the valve.

BC.

Click to expand...

No. Centrifugal force acts away from the axle of rotation. For example, a wheel weight stuck inside the rim will be assisted in staying put by centrifugal force.

To release air from a tire (that has a typical valve stem) the valve pin is pushed away from from the axle - the same direction that centrifugal force acts.

MikeM. said:

You do have all 4 valve stem caps on? I'm surprised but many motorists seem unaware that the little valve inside the tire stem is not designed to hold air while driving (only long enough to put the valve stem cap on). The way most valves are mounted, the centrifugal force created by a spinning wheel works against the sealing of the stem. And road bumps and dust/dirt compound the problem. So, always use caps that have good seals.

Click to expand...

Hmmmm.....I don't think so. I agree that centrifugal force would tend to open the valves, but they won't lose air because of it. I run my BMW at the track and normally leave the valve caps off so it is easier to check the air in the tires, which I do before and after each run. I don't normally lose air pressure. I run up to 125 mph on the tracks I run on and have never had a problem. These are whatever my local tire shop uses, not special valves. He always puts caps on them, and I take them off. I do agree that dirt is an issue for getting in the valves.

They are called dust caps and protect valve from debris.

Correct the duct caps can help air loss but only if the valve is leaking, in which case a new valve should be fitted, dirt can get under the valve seat.

CX-SV said:

They are called dust caps and protect valve from debris.

Click to expand...

I have seen them referred to as "dust caps" but the original term is "valve stem cap" and their function is two-fold;

1) protect the valve from dust and water
2) back-up air leakage protection

This is a good article that discusses the function of valve stem caps:

http://caraccessoryreviews.wordpres...pressure-what-do-you-need-to-know-about-them/

Mazda ships the CX-5 (and I presume other models) with two piece valve stem caps, the threaded plastic cap body and a neoprene o-ring insert designed to seal air pressure against the end of the valve stem. I am a believer in installing new valve stems periodically (or at the very least, new cores) because the sealing surface of the tiny valve core can harden and degrade over time allowing air to leak. More than once I've heard a small hiss of air escape when loosening a valve stem cap. That indicates that air had leaked past the core seal and pressurized the area behind the valve stem cap. With the cap in place, this is not a problem because there will be no more leakage once the pressure inside the tire is equalized with the air behind the cap. Without a cap in place, air would continue to leak. The funny thing is, I can put soapy water on the end of the valve stem after hearing the small hiss of pressure escaping but it is never leaking air. This tells me the air must be getting past the valve core seal only under certain conditions. It is likely that road shocks, centrifugal force and maybe even temperature variations need to combine to create the leakage. In any case, a cap with neoprene seal will effectively stop it.

A cap also protects against sudden failure of the tiny valve stem core which is known to happen. All motorcycle road racing organizations in the world require the motorcycles to have sealing valve stem caps on both wheels. I'm surprised there are still car racing clubs that do not require the same. Perhaps it is because sudden loss of air is more dangerous on a motorcycle. Still, sealing valve caps are cheap and easy insurance against air leaking through the valve stem.

Yes, the valve cap is only a temporary measure at best for air pressure seal if a tire valve is failing, (as pointed out in the info-commercial). Agreed, certainly an extra measure of insurance at minimal cost.

The Mazda TPMS system in the CX-5 (OP's topic) is a far more sophisticated and valuable measure of insurance.

Went from OEM 19's to aftermarket 18's and didnt even have to reset it.