The roads in TDP are suitable for any car. I did with my low clearance, 2WD car with no problems, even if it is raining. It is gravel, so drive slow, no more than 50-60 km/h, and you will not have problems with tires. The roads have many curves, the scenery is breathtaking, so you can think about average speed around 30 km/h. There are lots of wildlife in all roads, but if driving slow there is no risk.
From Hosteria Las Torres you go near Laguna Amarga entrance, turn right, then you have changing views of Los Cuernos, after a good stop is near Salto Grande del Paine, just a short walk from the road. If you want a better view, walk for about half hour to Nordenskjolt lake. Continue in the road, in the main intersection turn right, to Grey lake. You can walk straight from the hosteria in the direction of Los Cuernos, neat the lake shore. At the end, turn left, there is a trail to an excellen viewpoint for icebergs. You see the glacier far away, about 20 km.