Paranoid about wheel size

[cwilson]

I know I'm probably over analyzing this, but according to A&C, the recommended sizes for the wheels are as follows:

Front: 15x8 4.5" backspacing
Rear: 15x10 4" backspacing

I saw in an old post that someone was running 15x7 3.75" backspacing and said that the tire/wheel combo stuck out about .5". On the rear he was running 15x10 3.75" and the wheel was tucked under about .5". I may be having trouble with my addition/subtraction, but shouldn't the opposite be true.

The reason I'm wondering is that I ordered a set based on the recommended setting, but was told the best that could be done for the front was 4.25" backspacing, which would push the wheel out .25". This didn't seem like a big deal to me until I looked at the above wheel sizes. If a 15x7 3.75" sticks out .5", wouldn't a 15x8 4.5 stick out .75" and a 4.25" backspacing stick out 1".

Am I calculating something wrong? Maybe in misunderstood the original post.