Originally Posted by Cowgirls Boots
We used 2x8 pressure treated pine on our floors and no problems thus far.
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Because you have not had a problem with them yet does not mean you won't.
I am a professional welder, when I had my shop a HUGE portion of my business was trailer repair. Pine boards + Trailers will eventually = holes in the floor 100% of the time.
The difference in cost isn't that much and in the long run oak is cheaper than pine because you do not have to replace it as often.
There is a reason I refuse to use pine for a trailer floor of any kind because I have had it happen too many times where id fix a floor and 2 years later it needed to be done again.