Bent Wheel Rim?
 

I posted the other day that my rear passenger tire pressure measured at 26 lbs. It has harly been driven. Tonight I returned to the garage. It's down to 21 lbs. Tomorrow I re-inflate and go directly to the tire guy. I noticed I must have slightly scraped about 1/3 of the outermost rim of the wheel. Could there be a connection between that minor scrape and the tire pressure? Sure hope I didn't bend the wheel---just appears to be a very minor scrape leaving the edge of the rim a bit rough and black. Why black? I'm so sorry Z...

I doubt you bent the wheel, might have bent the valve stem though. Unfortunately the value stem is part of the TPMS, and so if it is damaged the whole sensor needs to be replaced. If it's just a bad core valve then they can fix that.

If the valve stem is damaged and causing air to be leaking, will the tire have to be replaced or is the valve stem repairable?

The valve stem is independent of the tire... but the TPMS aren't that cheap

Sounds more like a slow leak from a puncture. These tires cover a lot of real estate being the size that they are. The TPMS also has a seal that might need replacing, or the tire valve core might be too loose, or not seating properly.

Probably a puncture. Pull the wheel off and inspect the tire closely.

can u put the tire under water and look for air bubles?

If you have a place that you can do that, sure. But you need a pool or a big tub---and an understanding wife). I spray soapy water on suspected areas. Come back after 2-3 minutes. If there is a leak, you will have a large bubble cluster.

I curbed my rear right wheel not long after I got my Z :shakes head:. You may have damaged the valve stem.

What A Relief!
 

I re-inflated my leaky tire this morning (now down to 20 lbs.) at a nearby convenience store and visited by buddy, the tire guy. He removed the wheel and immediately saw a nail in the tire. Ten minutes and nine dollars later the tire was plugged, pressure re-checked and I was good to go and on my way. I'll check the pressure daily for a week or so to make sure the plug is good and that nothing else is wrong. I'm confident that the very, very minor wheel scrape did not harm the valve stem and that this is the end of the story. I hope the tire plug can be expected to last for the lifetime of the tire. As I said, I'll monitor the pressure daily for a week or so and weekly thereafter.
Benefit of this experience is I am now attuned to checking the tire pressure weekly or so, though I never concerned myself with it in my other cars.
Next project is to get to the wheel repair guy to have that small "curb rash" scrape removed. Gotta' keep my Z perfect!
Thanks everyone for your thoughts and your interest. Z Forum is great.

Plugs can do alright ... depends on the size of the nail. I had a moderate sized bolt (~1/8") embedded in the tire of my daily driver. Spent 10 bucks getting it plugged. The plug held about a year until I started getting a very slow leak. Eventually took it to my dealer and they patched it proper. Haven't had any problems since.

What do you mean "patched it proper?" If the plug is not the best method of dealing with this, I'm on my way back to the tire guy for the patch method. It was a small nail, maybe 3/8 inch to 1/2 inch long and very skinny. But I'd rather spend a few more dollars now and get this thing done "right" the first time and not have to deal with it again.

Tire needs to be dismounted and plugged from the inside.

Long term the consideration is corrosion of the steel belts that have been now exposed to the environment. Takes a couple of years for that to be an issue however. I burn through tires way quicker than that.

It looks like your nail was very small. I had a self tapping bolt with threads embedded in my tire -- between 1/8" to 1/4" in diameter. Much larger than your nail.

In any case, as ChrisSlicks said, the preferred method is to plug the hole from the inside and apply a patch.

yea used that trick on bike tires.. and smaller tires and pool floats