I can endorse your recommendation of Pirelli Scorpion STRs. I had them fitted to my 2004 Volvo XC70 when I bought it used. I have never had a moment's problem with them even on quite snowy roads over the winters of 2009/10 and 10/11. I haven't really tried them off-road apart from the occasional venture onto a grassy sloping track where I had no problems. Also, they are not too expensive and I got 30,000 miles out of the front pair, which I thought excellent for such a heavy car.