In order to fill out the Sebring flares, we planned to use 225-series tires, the widest thing available for a 15" rim.
The outer half of the inner fender was cut out and new fender wells were fabricated to meet up with the outer fender.
On tope of this, the flares were bonded to the metal panels with 2-part panel adhesive, then reinforced with glass-filled polyester resin. The resulting fenders are stronger than the originals and fit the new wheels with just enough clearance for the tires at full deflection.