195/65R15 K9A (hard compound) mounted on subaru wheels from an outback sport. The hard compound is still softer than re92's. The whole package weighs 45lbs. The wheels are 19lbs!
So far I have tried these tires on 3 different surfaces.
Frozen/muddy gravel: 30psi on all four. Better grip than re92; especially when moving sideways. You can scrub off much more speed by sliding sideways than you can with the stock tires. The stockers just slide along uncontrollably on the loose stuff. You can actually steer too; still some understeer, but response is better than stock. Under braking, an individual tire is less likely to lock up. I think the most grip was found in the medium, less-frozen areas. Definately good in the soft/muddy gravel. They also seem to handle sharp bumps (rocks) better, but large ones make the car feel "floaty" since my tire/wheel combo is 9 pounds heavier than stock. After one rallycross event, the tread had scratches (not quite cuts) and rounded edges.
Grass: 36psi on all four. Here they seemed to have the most grip. It wasnt short, thick soccer field grass, but tall wild grass in a field. In soccer fields my car understeers like crazy. (poor kids) With the R700, the car actually turns in. Im not going back to the soccer field to test the kumhos, but I assume they would be good. I was especially amazed on how much speed could be scrubbed off by sliding sideways. It was better than using the brakes in a straight line. As my path wore down to the dirt, grip improved. It seems to me that these tires work the best in terrain soft enough to allow the tread to fully sink in. This might be why they prevented sideways drifting so much. Eventually, I had to steer/slide the car, instead of slide/drift through corners because I thought I would flip the car on a bump. They actually worked that well. Less sliding was much faster too.
Pavment: 36psi Here, the package weight was most noticable. Acceleration suffered, engine braking was reduced, and any jerkiness at low speeds was severley dampened. Sharp bumps like cracks in the road were more subtle, but again, large high-speed ones made the car "float" up and down more. Steering response was wierd; kind of like a rubber band effect. Basically, it had a delayed response that "caught up". Cornering grip was not bad, although I didnt want to scrub them too much. Also it would be hard to tell since they have a tall, squirmy tread. In a straight line they are not too bad, although you can feel them squirming with small steering imputs. They sound like a big truck on the highway. I only had them up to 75mph, but I felt perfectly safe with them. They didnt seem to wear as much in 10 miles on the highway as they did in a day of frozen rally cross, but the scratches on the tops of the tread blocks were all smoothed out.
In general, I think its a good tire for the price. Better than a snow tire in probably everthing but snow. I think it works best on softer terrain where the tire can actually move the surface rather than glide across it. A snow tire will probably out last an R700 on most surfaces. Hard packed gravel would surely wear it quickly.