on most cars the stock tires usually suck. Even when I bought my truck it had some crappy BFG's (Rugged Trails) and they wore out crazy fast and were NEVER very good. And those tires were damn expensive about 1200- $1400 for a replacement set.
Put some REAL BFG's (Mud Terrain) on it and they have been there ever since, about 60k miles of them and they still have lots of tread.
I expect crappy stock tires on the focus but so far they seem to do alright for my daily commute.