" I have quite big feet (45/12US/11UK)
Should I buy a "wide" board? becasue some sellers trying to convince me
to do that.
I prefer free riding with board abt 160cm. "

With size 12 dogs at the end of your legs, you will probably need a
"wider" board. Some things to consider:
1. A wider board (waist width) will generally be slower edge to edge
than a narrower board. During your first and second year, this may
not be important, but as you get better, it will be important.
2. You like free riding, which is generally o.k. with a wider board,
as you aren't trying to transition into a turn as quickly as someone
would on a freestyle or park/pipe board.
3. You can get bindings that raise the toe up, like on a ramp, to
keep the toe-end of your boot out of the snow. Many bindings have
this feature now. There are also Palmer binding platforms that raise
the binding off the board a 1/2 inch. Maybe a good idea. Get your
toes out of the snow, and maybe you don't have to go so wide.
4. The more advanced the angle on your stance, the less your toes will
drag. As in, +18 degrees, +10 degrees. However, I generally recommend
that newer riders keep a more neutral stance, like +8, -2 degrees.
Its personal preference, but more neutral lets you ride switch, bumps,
jumps, park, rails and just about everything easier...except bombing
the hill, aggressive freeride style.

Good luck!
Jason