Fitting Wheels

[Evil Stu]

Hi guys,

First post here from a long time lurker.

I'm upgrading my 70 GTO from 15" to 17". Reading up I found that some say I can fit up to a 275/40/17 on a 9.5" wheel (5.5" BS) on the front and a 315/35/17 on an 11" wheel in the rear. Measuring I figured that was pretty tight on the back so I decided to be cautious and order ONLY the 9.5' wheels figuring iif my measuring was wrong I could always run 9.5" on the rear too. So I have the 9.5s here and I put them on the rear to have a good look before I order either 2 more the same or 2 17x11s.

Problem is I'm not sure still. Anybody here done this before can tell me what I'm looking at? I snapped a few pics and I'm hoping someone with more experience can tell me if I'm wrong in thinking that this is about as far as I should go.