Ok, so I've searched and the answers I found are all different and don't make sense. These are for my 1992 s10 blazer.
I'm looking at wheels, 15x8s front 15x10s in the rear, the specs area as follows:
15x8, 3.75" backspacing with -19mm offset. 15x10, 4" backspacing with -38mm offset.
Will they fit w/o rubbing or sticking out? I will run all 15x8s if needed. front tires are 225/60R15, rears will be 255/60R15. someone posted a chart for best backspacing/offset combos and both these wheels are on the money there but other posts say the 15x10s need to be 5.5" backspacing and the 15x8s need to be 4.5" backspacing so which is right? Please help me sort this out before I buy wheels that dont fit well

 

would be best to use same size, that would allow a good rotation schedule

a good compromise would be the 4 in backspace. with those size tires you should be golden

 

the 15x8s have a 3.75" backspacing and its the only backspacing available

 

Those specs (in bold) would be more in line with a 4WD vehicle because of the wider axles. With a 2WD Blazer, the stock wheels have 4" backspacing and zero offset. 15x8 with 3.75 would work quite well. They'll sit a little bit further out than the stock wheels but shouldn't be enough to cause any sort of fitment issues.

I would stick with all 4 wheels the same for rotation purposes

Here is a good link that can compare various aspects of different wheels and tires. Plug in tire size and wheel specs and it will show you exactly what will change.
Custom rims, wheel tire packages for your ride - RIMSnTIRES.com

edited to add: Have you lowered your Blazer? I just looked through your album and it looks a little lower than most. 15x8 and 3.75bs will stick out 1.25" more than stock wheels would which could be more critical on a lowered vehicle than a stock height one. Perhaps someone with a lowered 2WD can add a little more input

 

The tire spec's sure seem to be rather narrow for the rim widths, IMHO.

 

It is a 2wd, it was lowered before but wasnt lowered correctly so its stock hieght again. If it gets lowered again it'll 2/2 or 2/3 so the 15x8s will stick out 1.25" more than stock? will they still fit under the fenders or will they stick outside the body?

Thank you mdehoogh and the rest of y'all for clearing this up. I will save up some more cash and order the wheels as soon as I can (needed tires bad on front and they aint cheap anymore)