how low to go
 

hi there just put 18in alloys with 215/35 tyres on my 1992 jap import subaru impreza as it had 17in on so i thought the 18in would fill the arches but now it sits to high i,am just putting on lowering spring for just now would be grateful if anybody knows how low to put it without the tyre rubbing the arches 30mm/35mm/40mm thanks

With the tyres you have the rolling diameter should be the same as the standard wheels, or thereabouts. I'd not go lower than 30mm otherwise you may upset the handling. As for tyres rubbing - it depends on the wheel offset/tyre maker/suspension/arch rolling etc etc.