No (measurable) effect. The patterns (it's not tread: it doesn't touch the ground) on the shoulder/side of some/most GP tyres has been suggested beneficially to affect the transition from laminar to turbulent flow on the top of the front tyre, thus minimally reducing air drag (not rolling resistance) at higher speeds eg 40+kph. But it's been suggested (and is probably true) that this is by accident and not by (Continental) design. And if this is an effect the rotation direction will not make a difference.