Michelin update, as of 22 Sep 2022; mid-day.
Finally, some potentially good news after a phone call with Michelin HQ that lasted just under a full hour.
Now that we're approaching ~3 weeks from my initial input to Michelin on this issue, and over two weeks since I filed a formal email reply with photographs and links to this thread (and others), I had had enough with their "crickets" response.
I called the Michelin support number for warranty claims (866.866.6605; which ALSO works for sending them texts apparently) for follow up and to see what was going on. Their "Radio silent" reply was just plain rude.
First level CS reported replacement 21" Tesla spec tires coming in, you guessed, "about four weeks." (It's the answer for any and all questions at Michelin;-)
I explained there was a massive "Firestone Level safety issue here" and requested a supervisor as this greatly needs some escalation. Finally reached a nice guy "A," a 20-year+ veteran of Michelin, who started by looking into the tire supply issue (they always begin there). He reported that many, many Tesla tires are coming into the US by early October, and to consumers by mid-October, assuming all goes well.
I thanked him for his efforts on that end of the issue, but then redirected our conversation to the safety aspect of what is going on here, particularly the "ticking time bombs" of what I'll call "pre-accident tires" that are on the cusp of exploding at high speed, without notice or warning. He finally stared digging into my photographs, and possibly some on this thread (and there are many, many scary tire photographs here; please feel free to add yours!), and realized that this is an inner sidewall wear/defect, and NOT a treadwear issue per se.
I explained that it IS NOT AN ALIGHNMENT ISSUE either as the rear camber on a Model S is fixed/not adjustable, despite the number of people here paying big money ($300?) for alignments which do absolutely nothing to address the issue.
I emphasized that the average Tesla Plaid owner is NOT going to be on his/her hands and knees every other day looking at their inner rear tire sidewalls, and that only SOME of the tires manifest impending failure with a slow air leak. Furthermore, running an already defective tire at low pressure only exacerbates the problem as heat is the enemy of tires, accelerating tire degradation and failure.
I dare say that he was the first employee at EITHER Tesla OR Michelin to "get it" when it comes to how much danger is laying in wait for an unexpecting MS driver . . . .
The net result was that he was going to escalate this to his supervisors at Michelin, although it would have been far better to send a straight-to-Michelin's-Safety-and-Legal-Departments memo. (I don't think he quite understands just how expensive a punitive damage claim can be when a company has repeated inputs regarding a major product defect, yet does nothing to investigate further. There's no malice needed, just a normal yet grossly incompetent internal communication process will do it . . . ).
Net result: he'll escalate the issue to his supervisor, but who knows if he or she will "get it" either.
Haven't followed up yet with a NHTSA safercar.gov safety filing yet, but will do so later this week.
If only Tesla had a safety input system perhaps they might care a bit, but the two SC's I've visited just shrug and suggest an alignment, and they don't have any tires anyway. So it's "Next customer in line please!"
Sigh.
Suggestions:
1. A call or text to Michelin (866.866.6605) for EVERYONE one on this thread. Emphasize that absent knowledge from this thread, there is almost no way for the average Tesla owner to know how close they are to a high-speed tire failure.
2. Safercar.gov filing to see if perhaps the NHTSA can reach a human at Tesla that might get the risks posed here.
3. Sadly, we'll all be on our hands and knees looking at our inner rear tire sidewalls for a long time to come.