Coming off, you shouldn't need any lube at all. Get the bead down in the rim well. I usually kneel on the tire to do this while using two irons on the opposite side to pull the bead over the rim. The rim is designed to allow adequate clearance to do this easily as long as the bead is seated down in the well. If you want, cut a couple of wood blocks to put between the bead and rim to make it easier to hold it down. If you have to exert a lot of force, STOP. You're doing something wrong. There's a steel cable in the bead, and it does NOT stretch.
Going back together, I use either Windex or Fantastik as lube.
10 Duc Streetfighter S (black)
67 Triumph Bonneville TT Special