New wheels now slight rub on rear arches

Just fitted 15x8 BBS replicas to my 89 cab, but there's an occasional 'rub' on rear arches. Only happens with passengers in car on 'not so smooth' roads. Would you recommend fitting 'stiffer' rear shocks to decrease the amount of deflection over bumps and perhaps increase ride height slightly? If so, which shocks would you advise me to get? Thanks in advance.

My advice would be to use wheels that fit, ie don't rub. As I see it stiffer shocks are stiffer on rebound as you need the initial give when hitting a bump, but saying that gas shocks do seem to offer a bit more resistance as they try to stay fully extended un like conventional oil shocker.

Best option is to roll you're arches to give clearance. Other option is to choose narrower tyres.

Stiffening suspension just to prevent rubbing is not a good idea, as is increasing ride height.