American Racing TT-M wheels

[pv-camaro]

hi,

question: i am looking for some new wheels, and i like the the American Racing TT-M.
My question is, they make them in 2 different sizes (17-9" is the most common), i was looking at the 17"-8", but i don't know if they will fit.
The offset of the 17-8" is zero ??

the wheels are for my 2001 3.8V6 Camaro, the 17-9" needs tires of 275/40/17but i want to use 245/45/17 and they fit better on a 17-8".

And i don't know what "backside" means ?

see picture:

[dklowrider]

if you lay a wheel face down and lay a straight edge across the wheel, you can measure from there to the mounting surface on the back of the hub. that measurement is the backspacing. the more backspacing, the more the wheel "tucks in" toward the car. less backspacing the more the wheel will stick out with a corresponding bigger lip on the outside. offset is the relationship of the hub mounting surface to the center of the rim. you can see by the specs that with zero offset [hub in the middle of the rim] you have less backspacing which would have the wheel sticking out farther, probably causing rubbing when turning if they are on the front. but they are an inch narrower which gives you a half inch less to the outside.
so if you have 2.27" less backspacing, and a 1" narrower rim, you should have a net of 1.77" more wheel to the outside.
offset is mm, backspacing is inches. not sure why.
if you get 9" wheels you can use the 275/40 because they are the same diameter as the 245/45. i think you wont like the look if the wheels are sticking out that far. the 9s are a perfect fit.