Joe.........does it really matter??? Unless yer a sphincterly challenged originality inspector, be thankful they hold air. Many rear tires are also loaded with rust inducing calcium chloride (CaCl) water for added traction. They usually leak from the innertube valve stem. There are other alternatives to CaCl, such as RV toilet anti-freeze (non-poisonous to dogs which like the sweet poisonous automobile anti-freeze); sometimes you can gitt "buys" on windshield washer squirt'em water (contains alcohol so it doesn't freeze) There is also "beet-guard" made outta sugar beet pulp. Unless you're plowing; you probably don't need the added traction inducing fluid in yer rear tires. And unless yer ag-bar tires are sloughing their bars ...or... you are besotted by the smell and look of $500 tires, save yer money.
As fer the 1-rib vs 3-rib front tires; most came from the factory with 1-rib for eazier steering; 3-rib has a little bitt more "capacity" and were often fitted for N's with front loaders. ........HTH, tireless Dell