Sometimes you get stuck no matter how many tires are driven. The way your soil is can play a big part. I back my truck and trailer onto my grass to turn around most of the time because it is better than backing down my 700 ft driveway. The last time I did this my 4x4 with mud tires was spinning all four and would not move the trailer. Granted it is I slight slope but the main reason is the grass and soil was wet. The soil in my yard turns to slime when it is wet. To get it it out I got on my tractor and had my wife drive the truck. Because of the angle of the pull the truck slid sideways which freaked out my wife.
Now that the soul is dry it is like concrete.
