I've found that the Tire Rack is very conservative as to what they list as recommended fitment for wheels and tires. Which is a good thing, since you know that any wheel/tire combo they recommend will fit.
I know several people have used a 235/45 tire, but I always play devil's advocate when people are looking for tires. I know you know that wheels/tires are unsprung weight which affects performance a lot more than weight in other places. Why buy lightweight wheels and then get heavy tires?
I see that the Tire Rack currently recommends a 225/50/17 tire. I'd personally go with that size. Why? More than likely the tire will
weigh less than a 235/45, more than likely the tire will
cost less than a 235/45, and you won't have to worry about the tire being too wide to fit your SHO.
On my SHO I actually have 215/50/17 tires. They actually look wider than they might seem on paper, because my wheels are 7" wide, so the tires have absolutely no sidewall bulge. They look a lot wider than my 215/60/16 snow tires, which theoretically should be the same width. And one thing I can tell you is that I have never been able to find the cornering traction limits with my tires. I know I would have absolutely no need for a tire any wider than I do right now, because like I said I have never lost traction or even heard as much as a squeal from my tires even taking freeway ramps rated at 30mph at speeds up to 70mph.
In the end obviously you have to make the choice, but I just like people to see that there's a lot of options when it comes to tires, and it's best to sit back and figure out what your intentions are with choosing a particular size (performance/looks/etc).
