Hokie,
I could tell a huge difference with the rear tires filled while using the 5' scrape blade. Didn't spin the tires near as much. Didn't have to feather the 3ph until gravel got close to the top of the blade.
I think it was Ernie that said one gallon of antifreeze per tire. I purchased the adapter from TSC, the enviro safe antifreeze from AA, and took about 20 minutes per tire. Jacked up the rear end, took the valve stem out, and filled. After that just check air pressure (while still on jack/stands) and put the appropriate tire pressure in. I filled the tires to where the valve stem was at the 2 o'clock position (just above the center of axle). I couldn't tell you how much weight it added /forums/images/graemlins/confused.gif
Fig