Ok so two weeks ago TPMS goes off on my car. I figured it went off since it was the first very cold day we had (a 30F cold front rolled into town). All the tires looked good so I drove about 5 miles and filled them all up to 38 PSI (they were already warm so I filled them a little extra). TPMS went off shortly thereafter and I thought I was fine.

Three days later it went on again. This time I measured all tires and realized the right rear was the only one that lost pressure (it was at 22 lbs or something). I then spotted the nail, drove it to the tire shop (Discount Tire), and they patched and plugged it for free (as they usually do). Fortunately, the nail was in the middle of the tread and was easily fixable.

Fast forward to this morning. PS - the last time I drove the car was last Tuesday since I went out of town for the holiday. Anyways, about 1 mile out of my house, TPMS goes off again. I go another mile to the first stopping place and observe the left rear tire is visibly low, not on the ground low but "VERY LOW". I drive another 1.5 miles or so to a gas station, but their air thing is out of order. I drive another mile (probably a total of 5 miles now), and fill it up. My tire guage isn't registering anything (less than 5 pounds), but there is some air in the tire. I fill it up to 40 and begin looking for a nail. I can't find one; I roll the car, search again, can't find one.

Anyways, I just checked my pressure and it's 36psi now and it's been sitting for 8 hours. However, I found a nail this time. It's in the middle of the tread and is repairable.

My concern is my 5 mile jaunt with the tire pressure low. I drove on a flat once (don't know for how long), but I ruined the tire from the inside (wheel rubbed the inner tire to where there was a clump of powdered rubber in the tire. Now granted, this tire was VERY LOW it wasn't flat. Flat by my definition is like in this picture:


I can't describe how my tire looked but it was visibly low but not flat like that. There wasn't any ripple in the sidewall, but if the sidewall height is normally 2.5" (which is just my guess), mine was probably at 1.5-1.75". Where as flat would be 0.5-0.75".

If you don't know much about this, please don't post the obvious crap like "get it checked out." or "you're screwed." unless you have experience with this. It's going to the tire shop tomorrow morning but needs to drive 30 miles home and 15 miles back to the shop tomorrow morning. It's got 36 cold pounds in it now and it drove 30 miles this morning without hitch. It's just one of those things that's going to bother me since I'd rather not spend $400 on a new tire that only has a few thousand miles on it. The good news, TPMS saved my first tire, and if this tire is able to be saved, then it will have saved this one as well.

Thanks!

 

The Potenzas have a very soft rubber compound (hence the low treadwear number rating) but the sidewalls are fairly rigid so it's hard to tell when there's very low pressure in the tire. You really can't tell without observing the inside of the tire but I seriously doubt there's damage to the tire if you were driving the vehicle as careful as possible to get air, not hitting potholes etc. and keeping the speed down.

I had a similar incident w/ the TPMS and it really is a great feature, I too was annoyed at first as it seemed like all 4 tires were full, but one was 20 lbs lower than the other three ( I keep mine at 40psi). This feature is even more important w/ our low profile tires as it's almost visually impossible to see a low tire.

 

Well I did have to get on the highway to get to the fill station so I did get to about 50 but only for probably about one mile, otherwise it was 20-35.

As far as TPMS, it'd be great if it gave you a per tire readout like GMs do, but this is a whole lot better than nothing.

 

As long as you dont see any buldge or bubble on the sidewalls after you get it patched and bring it back up to the correct psi you should be ok.

 

On my Z the tire looked fine from the outside but I had scored/burned a lot of the inner sidewall off when it rubbed with the rim.

 

I was worried about the same thing one time. I had just brought my tire in to Les Schwaab because they were right where it happened. They weren't busy, and I asked if I could come back and see the inside of the tire because I was worried they wouldn't look close enough. Turned out my tires was shot from the inside because I too had driven a few miles on a very low tire. He said he would have told me that...I would venture to guess that it varies from shop to shop and from service tech to service tech.

I think that in this situation it just depends, and you'll never know until you get the tire off and inspect it. So just make sure they know your concerns and they look at the tire specifically for that or they might breeze through the patch and not even look.

 

How low was yours and how far did you drive it?

 

Honestly...it looked about the same as yours and I drove it about 5 miles...maybe a tad more. I wasn't riding on soft sport tires(this was my other car not my G) but the tires were old and I think just detiorated easier than a normal all weather tire.

 

That picture isn't my car, it's an example of a truly flat tire, my Z's tire looked like that and it was ruined, my G's was substantially better so I'm hopeful. I'm just concerned because it was so low that the tire guage wouldn't reliably register any air. It would show like 3-5 PSI, I don't know if I've ever driven on a tire that low (besides being totally flat).

 

I had to replace a rear tire on my 07 6MT Sedan after driving just a couple of miles with the tire flat. I didn't think it was completely flat, but apparently the sidewall is stiff enough that it still look like it has a little air in it when it doesn't.

I drove two miles, put air in and drove two miles back home and removed the wheel and took it to Discount Tire. Turns out it didn't matter that my driving on it damaged the sidewall because the screw that was causing the leak was right at the edge of the tread where it couldn't be patched.

 

That sucks, crossing my fingers here. My nail/screw is in the middle of the tread so I know that part of it is repairable. The tire didn't smell like burnt rubber when I put air in it, sometimes they smell bad after driving on them if there's internal damage.

We'll see tomorrow. Looking at the picture I posted in the original post (which is of the same wheel/tire as mine), it's obvious that one is flat. It's VERY obvious. Mine was no where near that obvious, but obvious none the less. There was a substantial difference between the tire in that picture and mine, but mine was REALLY low, further proven by my barely readable PSI readings on the tire guage. Like I said, we'll see.

 

I wouldn't worry about this too much, tires are designed to withstand a certain amount of this treatment.

People drive on low tires all the time, and continually fill them up. Its not always the safest thing to do, but as long as the sidewall integrity hasn't been compromised, and you are not driving hundreds of miles on it, it should be fine.

Based upon the title of your thread, you seem surprised the TPMS sensor works. Why wouldn't it? This is nothing special, they are only putting it on because the government is making it mandatory shortly.

The system sucks, it forces you to check all four tires. Even GM doesn't make you do that.

 

Well the tire shop just called and said they patched it and it's fine. I told the guy that I was concerned about driving on it when it was a pretty low, and he said they'd check it out. Anyways, another guy called and said it's good to go.

Good news! Now let's pray I don't find any more nails!

 

they are run flats, so you should be able to drive 50 miles on them, thats why it seemed like there was air in it when there wasn't

 

Coppell, although the RE050A is offered in run flat, the G35 was not equipped with the run flat version. http://blogs.edmunds.com/roadtests/1562

There's a blog post down there that says so. Also, look at the picture of that RE050, it definitely wasn't run flat. It's possible mine had a run flat (and that'd be awesome), but several google hits say the G35 is offered only with the non RFT RE050A.