Looks like this is my last ST66 front for the 250. It's not a full 16" and won't seat properly all the way around.

When I emailed Pirelli they tried to blame the install (which was done THREE TIMES to make sure it was their POS tire that was the problem). Motorcycle superstore said I'd have to pay return shipping, then hope the pirelli rep considered it defective.

Guy I spoke with had no idea what would happen if the Pirelli rep decided it was fine.
This process will take 6 to 10 weeks, so in the mean time I have to buy another tire.
Therein lies the complication of buying tires online and having someone mount them for you. That's also probably why some dealers won't do that.
I had something similar but different happen. The tire that was on my bike (???) came apart...while I was riding it. I can't remember the brand but Bridgestone comes to mind...anyway, I was riding real slow like across some RR tracks and I hear Psssssssssssssssssss and my tire goes flat very fast. I figured there was a metal spike on the tracks or something and expected a typical flat tire scenario. Upon further investigation, the bead separated from itself where the steel belts (or whatever is going on in the bead) actually met. It was the weirdest thing. When I took it back to the house and tried to put air in it since there was no obvious puncture, the sidewall just bulged out like a balloon until it went pssssssssss again. I took it to the dealer and they recognized the severity of this situation and handled it. I don't know if they were afraid since they were the ones that mounted it but the service guy said the manufacturer ponied up a new tire for me. I don't remember how long it took but it wasn't horribly long.
The terrifying part is that I specifically recall the day before doing a high speed pass w/ some friends. The bike was a 96 CBR1000F and I had it pinned and it was done accelerating. I saw 155 so I figure I was probably going about 140 on a tire that was ready to come apart.

You know that feeling in your gut when you realize something could have killed you but didn't...?
BillO