I got eibach springs put on my 94 rx7, does anyone know if i can properly fit some 18X7.5 rims on the car without rubbing and grinding?

 

Those are narrower than stock. You should be able to fit 18x9s at each corner with your setup, someone will have to verify (I run coilovers with 17x10s in the rear with no probs).

 

Your overall diameter should remain fairly close to the stock 16" wheels with the right tires (i.e. if your stock wheels fit, then they should). However, you will be going to a smaller width rim using 7.5". The stock wheel size is 16x8.

You'll also need to make sure you have the proper offset for the wheels. Stock wheels are a +50.