To start, that style tire does not swim well at all. Second, the rear tires are the most important to run backwards from traditional direction on the vehicle although all 3 sets are usually run that way. You need some rawhide I's, Esquire III's, chevrons, or argo tires to really swim. As for the water in the tub, you have some bad axle seals or bearings. Fill ththe tub with water to the top of the axle flanges and watch for it to leak out. That will tell you where to start.
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