My bed platform is made of OSB. I consider myself to be a pretty big guy. It hasn't caused us any probles. This also includes every RV I've owned since the mid 80's. The exception being pop-up campers. I think they are marine plywood because of potential exposure to the elements. The roofs on my houses have been OSB and have held me, snow and me with the snowblower. I wouldn't be concerned about the bed platform. As for tires, majority of the issues I have heard regarding tires have been on the heavier trailers. I can still understand some concern with these tires though but I think we are going to have to accept what any factory puts on the trailer unless your dealer can make other arrangements prior to ordering a trailer or you can negotiate different tires with the dealer.