I had 295/50-15's on mine. In theory, they can fit but back spacing is critical. Mounted on 8" rims, my tires measured 11-5/8" wide from sidewall to sidewall. My fenderwell measures 5 1/2" from fender lip to brake drum and 6 1/2" from drum to spring, giving total clear of 12" min. I got the back spacing wrong and it ended up rubbing my fender lip.
A wider rim with a lower profile might give a little more clearance by reducing the sidewall bulge, but it probably won't be much. I'd recommend going to 275's. Much better clearances and you'll loose less than 1" in tread width.