Wider tires = better handling though. The 195 tires on my car are great for fuel economy...not so much for cornering 9 and more importantly BRAKING!)
Tell that to the street prep Turbo eclipse and Cobalt SS (first two cars that come to mind) that I beat in auto-x with a 1990 Miata on 195mm wide S.Drives :awe:
Wider tires don't necessarily mean better handling. They are heavier will not respond as quickly to turns and will numb steering feeling at high speeds because of their gyroscopic effect. Unless you get an appropriately wider wheel the sidewall will be 'stuffed' or bent outwards, which will impact the the tires' response further, particularly on turn-in if memory serves. They
might make a
small difference in ultimate grip in a race/auto-x environment if the car is power limited rather than traction limited.
As for braking... again, heavier tires/wheels will negatively impact your braking ability. A wider tire could improve it, maybe, but it's not so cut-and-dried.
For street driving you'll never know the difference in handling, what you will notice is the reduced mileage and reduced hydroplaning resistance. Again, this is assuming that the car can't easily spin tires, which a 120hp/112tq Fiesta probably can't.
We can hand-wave this argument all day... my point is that the blanket statement "wider tires are better for handling" that many people make isn't always appropriate, especially if it pertains to a street car.