18"x 8.5" Mustang Bullit rims

[Denbow 99 GT]

I've been looking all thru the wheel section and cant find exactly what I need to know ..... I just picked up a set of stock 18" x 8.5" Mustang Bullits , tonight I pulled the rear wheel and put the rim on to check backspace, they are listed as 6.75 inch backspace and 45mm offset, HOWEVER, when the rim is on the car I have aprx. .5 inch between the rim and trailing arm ..... my question is how much will the tire hang out past the rim ??
I've noticed the mention of "spacers", I would prefer to keep the rims tucked as much as possible so prefer not to use them, will be mounting 245-45-18 tires
has anyone used this setup ? (pics would be nice)
the car is stock height.
really appreciate any help...

 

[Bio248]

the tires should be pretty square on that size wheel.

 

[Denbow 99 GT]

I kind of thought that, this is the first time for me with this size tires, and I didn't want to spend $$ on tires to find out that its not going to work or require a huge amount of modifications ..... I did search a bit more on here and found some pics of the exact rims on a GT, so I know they work now .... but that rim sure is tight to everything behind it.
I appreciate the reply ....