[mourati]

FWIW I can confirm that tyres fitted by the OEM's should be replaced with like for like tyres. When tyre outlets offer "deals" their kick back are from the wholesalers - also one should pay close attention to the weight and speed limits of any alternative new tyre as any rating that is lower than what's on your tyre placard will usually mean insurance is void in event of a claim - it's the first place most insurance companies go to when they look at your car. It's all about getting out of the claim.
I've always stayed with the Bridgestone POTENZA RE050A based on original equipment fitted to Titanium Mondeo's.
4 x sets later and the car has always tracked and worked as they intended - Ford spends squillions tyre testing multiple performance factors before they settle on a tyre.
I've seen many change their 18" tyres to other brands that claim better mileage and better performance - in all cases those that choice another brand had wished they stayed with the Bridgestone Potenza RE050A!