bias ply

So, tomorrow I pick up my new (to me) 1983 16 foot funlite. Looking at the original specs from the brochure, I see that it originally came with B-78-13 STC tires which are now a 175/80-13. The dry weight is 2K Lbs (can't find the GVW anywhere). The previous owner (or the one prior to him) has...