SX fenders are weak. As you surely know, the fender LIP roller will roll the FENDERS out on the SX. I don't exactly know why, whether it's just one layer, or it's just thin metal, or a combination.
If you want to go nuts on the Volvo 240 and you don't mind a little grunt work, drill & split all the spot welds on the fender lip. Then slice through the spare tire well, along the bottom of the quarter panel...from mudflap to rear bumper. Then snip away any remaining connective material (not much, if any) and the quarter panel should be free to be pulled (pushed) out. Use a 240 scissor jack inside the trunk, down in the spare tire well to push the panel out. Use a port-a-power tool or some sort of scissor or bottle jack to push the panel out at the top. Then fold in the outer lip so it's flat and weld the lip to the inner panel (I like to cut off the entire fender lip from the inner panel first). Once there are 4-5 points along the top of the arch that are spot welded, release the jack(s) and the panel should hold it's shape along the top. If you need more room at the rear of the arch, push it out with the jack and weld in a brace. They shouldn't be needed though, if you get some welds along the lip.
Here's our test subject...a bit rusty, made it easier. Tire is a 275/45/16 Hoosier A3S03...roughly 11" section width. No wheel, just making sure we could actually get that much tire under the fender.
255/40/17, 9.5" ET0. When measured at the point on the arch where it goes from green primer to blue paint, it's a ~1.5" pull. The leading edge of the arch isn't pulled at all.
This is my car with 265/45/16 on 9.5" ET3 rear and 245/45/16 on 9.5" ET-13 front. No rub anywhere. The rear is pretty tight along the fender lip, but I could fit a wider tire at lower offset. The front has plenty of room for more tire. I bent out the fender lip and shaped it into a single flare, then skimmed thin layers of bondo over the roughly hammered panel, sanded it smooth, and painted.