Use a high-lift jack to raise the frame enough to place long 2X12 boards under the tires, well lubed with chassis grease. Once the tires (even flat ones) are on a smooth surface your winch should move it, but only if you use 3 or 4 loops of cable and snatch blocks. A 4-line pull turns your 5K winch into a 20K. but it also decreases the speed by a factor of 4. This is a good thing! Just be sure your anchor vehicle is well-chocked (all 4 tires with BIG wheel chocks) so it doesn't get pulled backwards. Pull a little, reposition the anchor vehicle and slide boards, and pull again. I've used this method repeatedly to move wrecked 18-wheelers weighing 40 tons or more. Be patient, and pack a big cooler with bottled water if the weather is hot. You're in for some sweaty work!
Jerry
