The US market SH Forester (MY09-13) is fitted with a T155/70D17 temporary spare.
The temp spare in the US market MY2014 "SJ" Forester with 17" wheels is size T145/80R17, which makes it ~1.5" smaller diameter than the 225/60R17 road tires. The temp spare in the new Forester with 18" wheels is size 185/65R17, which makes it ~1.3" smaller diameter than the 225/55R18 road tires.
HTH,
Jim / crewzer