This is easier to answer if you already have the wheels picked out? Stock width will work with 15x10 (in a Malibu) with the frame notched to the seam. That will work with a 10 inch wheel with 5.5 backspace. The seam is even with the factory inner wheel tub on Malibus and most G-body coupes. Now, that said, other cars have different shaped wheel openings. Wagons and El Caminos have the largest wheel wells. An El Camino will take a 15x10 with a 4.5 backspace with a stock G-body width rearend (58 inches wheel mounting surface to wheel mounting surface).