Direction of warping wood?

Hi all....

this is off topic but I figure there are enough telescope makers/ woodworkers
here ...

..so I ask
.....

I am rebuilding a trailer in which the only part left is the metal frame....

I am planning on redoing the bottom of the trailer with wood planks....pressure
treated 1 by 8's....

So, lets say Iam looking at the end of a plank where I can see the tree
rings...and say on this particular slice I can tell that where the center/core
of the tree was lies ABOVE the plank as it rest flat on the ground...


In that position....as the wood ages and dries out over the years....are the
sides going to curl UP or DOWN?

Iam asking because I want the edges to curl down over time...ie I definitely
prefer the plank to become convex rather than concave...

Or do I need to flip all the planks over so that where the center of the tree
was lies BELOW the planks rather than above?

Thanks for any input!

Bll