A few things:
You're right, you have waaay too much hit rating for a bear tank, and you're still gemming for it. If you really want to gem for a threat stat, go for Expertise instead. You could afford to drop some hit gear too, if you have other alternatives available.
Spec into Primal Precision. That's so much expertise you're missing out on.
DPS should also be Misdirecting (And even Tricks, if it's that big a problem) to you as often as they can, if threat is causing wipes.
But generally when it comes to threat issues, you're looking at rotation problems over gear problems. Darksend has a guide on threat rotations already posted in the guides forum, so I won't blatantly plagarize him by copying it here. I'd recommend taking a look. =)
As for the issue of overzealous DPS dying on a pull...you can't fix that. That's their problem. If they want to be terrible, that's their repair bill. If they persist in being terrible and the raid leader isn't addressing it, then you're wasting your time. (And perhaps that's why their last tank bailed.)