Rules may have changed in the 5 years since the OP.

This is pretty ancient now, but in case anyone finds it in another 5 years... They wouldn't allow the poster tube on, or the poster without the tube. I had to cut it into 4, so that it could be rolled up small enough to fit into regular carry on and then stick it back together at the other end.

As ft101 says, things could have changed.

I'm a little late to the game here, but, since I posted in another RyanAir thread tonite, I came across this one . . . .

As a certified shopaholic :D, who ALWAYS has tons of "stuff" on the plane, I might've considered stuffing the poster tube down the back of my pants and wearing a big coat or jacket over top.

Does anyone thing this might have worked? :)

If wearing a black hat and a long black overcoat, and walking with a bit of a limp with the poster tube down your pants, people might easily believe you are Herr Flick from the old TV series Allo' Allo' that way :D should work!

I print all my posters on fabric now, as do most of my colleagues. The cost is slightly higher than paper, but worth it IMO.

Normally just fold it up and stuff it in my bag. Then hang it someone on arrival to drop out any creases.