Preheat oven to 350º.
Combine salt, cumin, paprika, pepper, cinnamon, and cloves.
Sprinkle on ribs, rubbing over entire surface.
Place ribs, bone side up, in shallow roasting pan.
Bake, covered 1-1/4 hours, drain.
As ribs bake, boil root beer gently uncovered until reduced to 1-1/4 c, about 20-25 min.
Remove from heat.
Stir in BBQ sauce, tomato paste, vinegar, mustard and W. sauce.
Return sauce to boiling, gently, uncovered for 1 min.
Remove, set aside.
Turn drained ribs meaty side up.
Spoon 1/2 of sauce over ribs.
Bake uncovered, 45 min. basting once or twice with remaining sauce.
Spoon sauce over ribs to serve.