Well, if you ordered struts that are direct replacements for your Impreza, those tires 215/65r16's won't fit because the distance from the lower spring perch to wheel hub center stays stock $--(unlike Forester and Legacy Outback struts which have more distance from the lower spring perch to the hub center)--$, thus limiting the maximum tire diameter. As for the spacers, they add more distance between the strut top and wheel hub center, effectively giving you more ground clearance and pushing your wheel down out of the wheel well (which could resolve some rubbing issues), but will not increase the maximum tire diameter that one is able to use on their struts as the lower spring perch to wheel hub center is unaltered. I don't have experience with GR-2's, but I would think that if they were OEM replacements then the suspension geometry would not be altered, just higher quality parts, so the solution would be to order GR-2's for the Forrester or Legacy Outback. The geometry on the Impreza suspension would be altered enough that Forrester or Legacy Outback GR-2's could cause you CV Axles to be stressed and not last as long, but there are reports of non issues as long as you have camber bolts in the rear (and possibly front) to compensate for the increased positive camber due to the increased length of the struts. If you stacked the 1" spacers along with the Forrester/Outback GR-2's, then you will definitely experience excessive CV axle blowouts. Please correct me if I'm wrong.