I rotate mine every oil change! 5k!! Most subaru dealerships say ιt don't matter!! Good ones recommend ιt!! Tyres last longer but you do replace all 4 at the same time!! Impreza uses a viscous coupling, so really needs the tyres to be the same all round!! Little differences lιke lighting up tyres
On a roundabout will be compensated for! But if you do 6000 miles on a set of tyres that have a 6mm difference front to rear! Imagine the difference in revolutions due to circumference?? Some say ιt's ok! I prefer to er on the side of caution!