They'll take a 15x8 wheel easily, and that width would be better for a 275 width tire.
A 275/60R15 will leave plenty of room; you could go quite a bit larger if you want.
With a 275/60 rear, I'd run a 235/60 or 245/60 front, on a 7 or 8 rim.
The current Road Runner is like that, and one of my previous ones ran 15x8s all around with 265/50 & 295/50s.
The 50 section sidewall's a bit short, though.