correct wheel fitment

Hi, I have an s13. My wheels are 17x8 with a +45 offset. Can anyone tell me what size spacer I need to run front and back to make these wheels fit flush.

get new wheels with decent offsets and stay away from spacers is my suggestion…
Not to point out my own rims for sale, but I have a set of Gramlights, 17x8.5 +30 all around and they were flush enough for me on my S13 but some would say they weren’t flush enough and could use a 5-10mm spacer.
Link here: http://www.son240sx.org/showthread.php?155688-FS-17-quot-Light-Gunmetal-Grey-Gramlight-57S-they-are-17x8.5-with-30-offset-all-around
The “flushness” difference between your rims and mine is 22mm on the outside to give you an idea of what spacers you would need

Depends on rims as well to tell you the truth. Different designs affect the way it sits.

Throw them on and measure the distance to the fender from top camber. You’ll grasp an idea of what spacers to run.
I wouldn’t say stay away from spacers all together but stay away from slip on spacers.
Use bolt on spacers so your not decreasing the amount of threads the nut is using.

It sounds like 25mm hubcentric spacers would be about right; I’ll measure like you said just to be sure. It also sounds like just buying correct offset wheels would have been the way to go from the begining but I have to work with what I have now. Thanks for the advice.