Yes, I still have over 5/8 of material left from the bottom of the bolt chamfer to the base. Think about how long your stock bolts are.
I'm also running 275/40 in the rear, and mine do stick out. I'm not aware that there were any different offsets on the 360 wheels. How well do you know the history of your wheels -- could they have been machined prior to you owning them? I think the offset value is probably stamped on the inner part of the wheel (I know it is on the 348 wheels). That would be the way to confirm the original offset of your wheels. Then you could measure to see if it is still at that value or if it has been machined. I also wonder how much changes in suspension settings could affect this. For example, positive camber would help the wheels "tuck in". But I think that much positive camber would be noticeable... I'm stumped... - Eric UPDATE: I just checked my wheels. The offset value of 38.95 is stamped on the inside of one of the spokes (easy to read even with the wheels on the car by using a small mirror).
If that picture next to your name is your car your wheels do stick out. I think the picture I originally took of the rear of my car somehow made them look worst than that actually were. I think I had just the right aspect ratio from the height where I took the picture. From the side, and actually from a rear angle the original set up didn't look all that bad, I just didn't like it that much. From what I have read all the axle set ups on 348s are the same - and I am sure the body is the same width. I think the tire and suspension set up may be the key to how come some cars look different than others. If you run 265 tires in 35 aspect, or even 40 aspect ratio the wheel set up will look different. Mine are 275 40, which is pretty wide. As for offset, the bigger the number the more the offset (distance from center). My original wheels were 68mm - that's a lot! The 360 wheels are 38.9 (that is stamped inside the wheel on the spoke). So you have about a 30mm difference in the amount between these two wheels, and the 360 wheels are 1" wider than the 348, so all in all you end up with about 42mm more sticking past the edge of the wheel with the 360 versus 348. If you like your set-up and they don't rub I wouldn't mess with them. I kinda liked the aggressive look mine had before I machined them (they actually didn't stick past the top fender of the car, I just think the picture made them look that way) but when you hit a dip in the road the inside lip of the top fender would barly graze the tire - I didn't like that. I am sure 265 tires or a lower profile would probably have fixed that, however, my tires were nearly new and I knew it wouldn't cost me anything to machine the wheels and get a more stock look on the car anyway. There are several threads on this, and group77 has some good information on his about the wheel set up. Dave
I bought the wheels from a 360 owner that replaced them with the CS ones, so no machine off there, I can't find any other reason .... and yes I am going to check the offset value and let you know.