I have used P225-60 / 15's on that size with good results. Kind of depends on the tire, all tires the same marked size are not created equal. Have one mounted and try it on all locations before mounting the rest.
Same here. 15/235/60 Like royce, I've used radial t/a's without any problem.
and maybe it's me, but I use a set of 16" wheels on road and autocross tracks. The 15s are much more comfortable to me on the road.
for what its worth
That's the backspacing on my magnums. I run 215/65/15's on a 15x7 wheel on my 69. No problems with this size. Check the clearance to the inside of your suspension. I had enough room to go to a 225 on the outside, but was concerned about the inner clearance to the suspension if i went any wider.