There is no correlation between a horse being tied and being handled.
Saddlebag, I agree that the two are related only as a matter of training. My point was that the horse uses rearing as a method of dealing with an uncomfortable situation. If the horse does it in one place that it is uncomfortable, I'd be concerned that the horse will do it in another situation that is uncomfortable.
A last resort we used for hubby's gelding was a "be nice" halter. He would stand tied for hours, then suddenly blow up and rear back for no discernable reason, other than maybe being bored. The halter had knobs on the inside where it ran behind his ears - when he pulled back, it hurt. He didn't do it but once after we used that halter. And no, he didn't hurt himself - his lead rope was tied to an innertube. We wanted the "be nice" halter to get his attention, not cause an injury.
Dee -- I like that. I had a mare like that. She'd be fine, just fine for the longest time and then one day she'd just blow up. Then fine again for weeks/months and then blow up. A halter like that would have been handy if I had ever gotten to a point where I thought she might be safe to haul somewhere...
DRichmond -- My thought was that a rearing horse should be tied higher than average, but after thinking about it, maybe the trick here is to encourage her to keep her head low and relaxed. This would also limit how high she can rear. I revoke my earlier statement.
To the OP - DR's comments about retraining to be tied is valid. It's just that you're working with a full grown mare, not a foal. And she already knows she can get away when she pulls. So far, I have always been of the mind to tie securely so that no matter what that horse can not break free. The halter won't break, the rope won't break, the post won't break... If she gets release at all when she pulls, that's teaching her the wrong thing. She should get release when she stops fighting. There is no need for you to have control over the rope to give her release. When she stops pulling and steps forward, she gives her own release.