Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: IB+ Gold, TK E+, Hyatt Globalist, Marriott LTP, IHG Diamond
Posts: 14,182
Assuming that your rollaboard is "compliant" according to Iberia's rules, you will be fine. Make sure you board with the Group 1 that comes with your Sapphire status to be sure of overhead space.
I've seen some American XXL "rollaboards" that have been denied by European airlines, though.