in simple terms the lower the ET number ( offset) the more the face of the wheel moves away from the brakes ( possibly catching wheel arch ? )
therefore the higher the ET the more the face of the wheel moves towards the brakes ( possibly catching on calipers or shockers ? )
+ or - 10/15mm should be acceptable but watch the rim size
Style 225M are ET 37 on the front and ET 39 on the rears, for an E85 your offset given a staggered set up is ET47 and ET50. This means that the fronts will stick 10mm further out and the rears 11mm