Does anyone have insight into the "sensitivity" of the TPMS sensors in our cars?

This morning I took my car to its first service and nothing was out of the ordinary when dropping the car off. A few hours later I received a message from the tech that a nail had punctured the rear passenger tire and was losing air at a fairly rapid rate (3 hours lost 8 psi). I was stunned as TPMS did not have any notifications and the tech calls me to tell me there is a "hidden" menu which shows the tire is leaking or some BS like that (I will have to call again and get him to repeat that but it made no sense to me so I will be updating this tomorrow morning)

Now I usually would suck it up and pay for the tires but the car was fine when I dropped it off, and since it's a c4 I need to replace 2 tires at a cost of 568 each plus tax. To top it off I only need these tires for another week as I have a set of HRE's wrapped in PS2's due next week.

Lastly here's a picture of the puncture which shows it's too close to sidewall to patch, and I would assume if I had driven any more than a few 100 ft with the puncture the nail would be deeper into the tire?

So my question to everyone is should I just suck it up and pay 1300 for a week with new tires or should I complain and walk around the lot to see if there are nails around their lot.

 

Why don't you plug/patch it? I think a plug or patch would work - at the very least you should try. Buying new tires only to switch them out in a week or so doesn't make sense.

 

Not sure I understand your question as it would seem your post is more about questioning the dealer integrity.. It certainly is possible you picked a nail up on the way to the dealer... And also consider you may have had a nail in there for a while, and then the mechanic saw it and dislodged it a bit, causing it to lead at a higher rate..

But as far as tpms. It is reasonably accurate.. I believe tpms is required to give you a warning if you are more than 10% low.. So that correlates to about 3 or 4 lbs.. So the sensors need to be probably 10 times more accurate than that... Somewhere I read (I think) the sensors had an accuracy of about 0.5 lbs which seems reasonable... And I once checked the internal reading and it was pretty close to the gauge reading... So I've learned to trust it and flip the menu up periodically on the multifunction display..

And the update rate seems to be less than a minute as I've added air and can see the menu readings change within a minute..

So my experience is tpms works very reliably and is a good thing to monitor on your multifunction display ( I certainly don't consider it a hidden menu).. It really is something you should monitor from time to time...

Sounds like you were just unlucky and picked up a nail just before arriving at your dealer..

 

As to your other comment about the depth of the nail.. From the pic it looks to be close enough to the edge that it may not have been pushed in flush with the tire surface...

That said, as I mentioned in my previous post, it wouldn't surprise me if the nail was in the tire for a while (leaking slowly) and then someone yanked on it a little which caused it to strt leaking at a higher rate.. Either way it needs to be dealt with and better to find out there than on the side of the road late at night..

 

Looks like it may be too close to the edge of the tread, although it isn't in the sidewall (but close).. I am all for plugging leaks though ( which it in itself is a controversial subject around here, that launches 100 post threads)

 

I'm assuming you'd need two because there would be too much spread in the tire depth if you only changed one? I had a similar occurance, had the car on a hoist for a different reason and there was a nail in the centre of left rear. Luckily it could be patched/plugged (I don't track the car or Auto X). When I had similar incident 18 months ago I was able to get by with one new tire as the tread depth difference was within tolerance.


I have seen the TPMS system give notice of a drop in pressure on both my car and on a rental 991. Not sure of the drop to get this message but I think something around 6-8 pounds.

 

Not sure if I would spend $1200 for a week's worth of tire use. I might even consider asking for a loaner or even renting a car for a week before throwing that money away.

 

According to the Good to know app..

1) the first level (yellow) warning comes on at between 4 and 7 lbs low.
2) The second level (red) occurs when 20% down. (I believe this is the US and Canadian Safety requirement). So that is indicated at > 7 lbs low..

That said, the system warning indications are based on which inflation range setting you set to on the MFD/Menu.. (full load, comfort or just normal.. as well as the tire type.

There is a huge difference in pressures between the comfort and full load. For example for a while I was only inflating tires to the comfort level. And if you set the MFD to normal, you immediately got a yellow warning... and if you set to full load you are in the red warning..

Moral of the story, your MFD/Car menu setting needs to match the inflation range you are using on your tires.

 

Yeah, after re-reading your post, if you are only going to use the tires for another week.. I'd just have the tire plugged..

It is a little bit close to the sidewall for my comfort but if it were for only a short period of time I'd just go ahead and plug it.. and just avoid any high performance activity and cornering. Given the short time, I wouldn't even consider replacing both of them. Granted you should replace them in pairs but for a week? naw..

 

Plug it. Call it a day. Drive it and wait for the new hoops to arrive! Post pics when new set is on car!!!!!

 

Don't purchase new tires. As everyone else stated, it's only one week until your new wheels/tires get here. Absolutely no point in spending north of $1,000. Use 1/10th of that and Uber it to and from work.

 

No way would I ray $1300 until your new wheels/tires come in. I'd rent a car for a week before I spent the money. This assumes that you can't get the hole plugged to last you the week.

 

As you are not going to track it I would patch the tire and drive easily for a week until you get the new wheels. It should not be a big deal but you might need to take it to a tire shop as the dealer probably won't do it.