Odd that your rears need changing so soon !!!!
underinflated so the edges of the tyres are worn?
If only worn on one edge of each tyre get the tracking checked.
On my 24, i always use Falken FK-451 (not ZE-512 crap), excellent grip, wear quite well (16,000mls front, >40,000mls rear), look pretty cool and a good price.
I found pilots OK but very expensive, but there again lasted longer, about same mile/?.
Yokohama tend to be a soft compound, i have both AVS Sport and A520 on my cossie, brilliant grip. Tested on road and track days.
AVS Sport would be my next choice for the Mondeo but running to many cars costs me too much anyway and they arn't cheap, but bloody good.
Hope this is some food for thought.
cheers