Clear as mud (Wheel Sizes)

I found 4 of these:
15x8 Black D window steel wheels 5 on 4.5 bolt pattern 3.75" backspacing.

Will they fit WITHOUT sticking out any further than the stock 15x7 inchers?
Can I use 30x9.5x15 tires if I wanted?

I tried to find this on the other posts - but it's just tmi for me...

Anyone help?