Did you try all the usual tricks for getting the bead over the rim, counsel? Did you push the valve stem up into the tire? Did you try pushing the bead on the opposite side over as far as possible toward the side you were trying to mount, in order to create more clearance to get the bead over the rim? Did you look all around the perimeter of the tire, trying to find places where the tube was caught under the bead? A little silicone spray on the bead, maybe?

Occasionally I've bought tires that were extremely tight, but I've always been able to mount them by using these techniques. I'd much rather have a tight tire than one that is too loose.

Good luck from your fellow pettifogger.