I think I saw it wear sometimes (low pressure and lots of negative camber)... But the thread was always faster to get a puncture than the sidewall... I could be wrong though...
Not to be anal (well.. that's not true... I mean to be :razz, there's 50 that heat but only 48 that wear?
Hmm, sidewalls really should be divided up and also wear... Why only heat & no wear? What if you lock up sideways, that should hurt the sidewalls in the right circumstances... ..... ....
The side of the tyre, that joins the 'tread' to the 'bead'. Where the writing is. I've seen (and done it) half the writing worn away from enthusiastic cornering with the wrong tyre pressures.
It's not unknown. I must admit it's rare, but I've seen it before. If you use cheap road tyres on a track (for a trackday for example) then it's more likely.
Yeah it's an eye-opener though. Deflation would probably be my first concern (bead can come away from the rim easily under these conditions, causing a loss of pressure or worse). The other problem is debris. Sidewalls are typically made to allow the tyre to flex and change shape as pressure changes, they lend themsleves to punctures by sharp objects rather wllingly. But I suppose many races or positions have been won by using "that extra little bit" (of luck).