Hi, I have a brick opening of 2270 wide and two side hinged wood garage
doors 1070 wide (total width 2140, no rebate) to fit. The height is not
a problem.
If I use treated 3 x 4 for the frame this adds 152 to the width which
is now 2140 + 152 = 2292.
So I need to shave off 11mm from each door width, plus some more for
clearance.

Questions.
How much do I need to remove for the clearance?
There is no rebate but I plan to add a plank down where the doors close
together to stop the wind whistling through. Are there any better
methods?

If I use 2x4 instead for the frame I am left with a gap of 28mm. Is
28mm enough for the clearance and perhaps a small strip of rebate wood?
Is 2 x4 strong enough to use as a frame?

Thank you