I picked up a set of brand new sabre wheels for my 05 str. There 19x8.5 all the way around. I can get a set of 255 40 19 really cheap, but i'm woundering if they would look outta place, since there taller than the stock tire size.

The other option I was thinking about doing was 245 35 19's in the front and 265 30 19's in the back. But these wheels aren't staggered.

 

255/40s have less than a 10mm difference in sidewall height than the stock STR sizes. 265 sounds awfully wide for a 8.5" wheel; I believe 255 is the typically accepted maximum width for a 8.5" wheel. If you put staggered tires on non-staggered wheels, it would look weird too.