Rim fitment
 

Well a 18x10 with 25 offset going on the rear without sticking out.

It most likley will not stick out, but you can always measure it to be sure.
http://www.tirerack.com/wheels/tech/...currentpage=91&

But the question is why do you want such a wide wheel? Don't you have a 7mge? Thats like 170whp.

Just wondering though of the weight of the wheel you are going for? You can always use wheel spacers to move the wheel out and give a more flush look and the impression of a wider wheel.

I already have 18x8.5 all around but I like the deep dish look in the rear. They sell the same rims I have also in 18x10 and was going to just buy 2 for the rear. And my supra is my daily driver so Im not building it for speed.

Well if it is the same wheel but only narrower then all you need to do is know the offset of the 8.5 and measure off it to see where the 10 will sit. But as far weight goes on the wheel it affects gas milage, ride quality, braking and steering feel. But if you are just after the look then who cares. I just thought you might not want to lose out to a minivan off the line.