i have 18"x7.5" rims with a 42mm offset,do i need spacers?they are on my box and they dont rub, but the rear rim has a clearance of about1/8" from control arm. any suggestions are appreciated!!!

As you can tell, since you have already mounted them, they aren't absolutely necessary. However, adding them won't hurt. It will not only give you additional clearance, but help reduce the inset look of the rear wheels.

I'd get One Tone Garage 10mm shims for therear, and also OTG 5mm spacers all around.