DRIVING IN MUD & SNOW
Slippery conditions can turn a normally easy trail into one that is nearly impassable. Snow is an obvious cause, but on certain soil types a rain storm can turn the surface of the soil into something resembling wheel bearing grease.
Driving techniques and tire requirements are similar for either snow or slippery trail mud. Wet trails are more easily damaged than dry trails, so Tread Lightly when it's slippery out.
TIRES, VOIDS, & LUGS
The most important factor in negotiating slippery trails is tires. The void ratio is the key. Void ratio is the ratio of the space between the lugs to the space used by the lugs. The higher the void ratio the better, for the most part. A higher void ratio helps the tires clean mud and snow from between the lugs easier.
Tires with high void ratio seem to be good for slippery trails because of their high void ratio, but they have only horizontal lugs on them. While these tires are good for straight ahead mud runs, the lack of vertical lugs means that they tend to make the vehicle may be more prone to sliding sideways in a slippery off camber situation.
Other high void ration tires are those which tires which have a vertical row of center lugs that goes a long way to prevent unwanted sideways movement of the vehicle. These tires have the advantage of increased flexing and deformation when aired down due to their radial construction. The flex helps the tires "stick" better by providing a larger contact patch and the flexing action helps them clean the mud out of the tread.
The best place to see how different tires perform is always going to be under real-world conditions on a trail ride.
Slippery hill climbs require momentum. When there is a patch of slick mud or smooth ice half way up the hill you must have enough speed to carry the vehicle over it and to the next area with some traction. You simply can't idle up a steep hill coated with mud or snow that's so slippery you can't walk on it.
If you get part way up a hill and forward movement stops you may find yourself going sideways or even sliding back down the hill with the tires still trying to go forward. Don't lock up your tires in this situation. Locking up the tires will cause you to lose all steering control. Always try to go into reverse and idle down. You may come down faster than you would like but you will be able to steer. If things are happening too fast to go into reverse go into neutral or press in the clutch and try pumping the brakes as you back down (never, ever, ever stomp on the brakes hard enough to lock up the wheels when in a slide, it is a sure recipe for disaster).
Don't have the steering wheel turned too far when pumping the brakes because you may find traction and cause the vehicle to turn suddenly. If you have slid sideways across a hillside but are still pointing upwards try pointing your tires back to the center of the trail and giving it some throttle. Lots of times the vehicle will move straight sideways across the face of the hill and get you to a safer place to back down. This will probably not work on an steep off camber hill. (Use caution when on any steep or off-camber hill, getting even a little bit sideways can put you in danger of rolling the vehicle, always try to keep the vehicle pointed straight up and down the hill whenever possible).
If you find yourself sideways on a hill, or starting to go sideways point your tires up hill and give it some throttle. This will often straighten you out. If you manage to get yourself completely sideways, perpendicular to the hill and feel as though you are about to roll, point your tires downhill and give it some gas and head down the hill.
The old off-roaders trick of turning the steering wheel back and forth when forward progress has stopped will often work when moving through slick mud or climbing a slippery hill, but sometimes you just end up going sideways across the hill. Be cautious of its volatile nature when trying this technique.
You may at times find yourself in the awkward position of having slid backwards down a hill until a tree stops you. You probably can't drive up or you wouldn't have slid down. A winch pull is always the best answer. If you have no winch you may be able to spin the tires while someone pushes the front of your Jeep sideways, allowing you to make an extremely sharp turn and head back down the hill. Make sure that the slope of the hill will help push the nose of the vehicle in the direction you want, don't let someone get pinned between your Jeep and a tree. If you attempt this move, make sure that you are not going to be in danger of rolling the jeep, and get the nose of the jeep headed straight down ASAP, using power as needed so you can control your descent.
Up or down, your best control is when both axles are perpendicular to the hill. A good rule of thumb is to send a winch equipped vehicle up first. Otherwise a stuck vehicle may block the trail completely.
Slippery, off camber descents present a different challenge. The most common problem is the back of the vehicle sliding off to the side. Locker equipped vehicles are especially prone to this. Always keep the vehicle in first gear low range when descending slippery hills. If the rear starts to slide out give it a little throttle and it will usually straighten out. If necessary, and if there is enough room, steer the front in the direction the rear is sliding. This will keep the front directly below the rear and keep you in control.
Rutted trails can be a problem for vehicles with small tires, but ruts can be a help in slippery off camber situations. If your tires are big enough to run in the ruts you will probably not slide sideways off the hill. If you have smaller tires try running with just one set of tires in a rut if the trail is wide enough. The uphill rut is usually a better choice. If you straddle a rut in a slippery situation it is just a matter of time until you slide in. If you are lucky your left tire slid into the right rut or vice versa. If you are unlucky you are probably squarely stuck in a rut made by someone with much bigger tires and in need of a tow strap or highlift jack.
Sometimes you will find a trail that has 2 tracks that have been used by the trucks ahead of you. These often become icy or slippery on a hill climb or descent. Try going to the side a bit to get some fresh snow or untrod dirt under your tires.
DEEP MUD & SNOW
Generally deep mud holes have ruts in the bottom and different parts of the bottom may be shallower and deeper, firmer and softer. Poking around the bottom with a stick may help you find shallow spots, but the best technique is to observe the vehicle in front of you.
In a wet mud hole the vehicle in front makes waves. Look at the bottom of the wave to see if you can find a shallower part to drive through. Sometimes a wave rolling across a mud hole will expose a shallow shelf you can get your wheels on. If the guy in front of you gets stuck and you have a similar or lesser equipped vehicle, don't follow his example. In a dryer, stickier mud hole it is difficult to judge how deep it is without driving out into it. The best bet is to go slowly and stop spinning your tires if you can no longer make forward progress. Put the Jeep in reverse and saw the steering wheel back and forth. Many times the side of the tire will bite and push you back out. Stay in your ruts as you back out. This techniques often works well for wet sticky snow too.
The fine art of hooking up a tow strap while stuck in the mud is often learned out of necessity. Anyone can simply hop out into the 30" deep mud (you can tell how deep by how much of your tire is showing), but a clever person can get to the front of their Jeep without getting excessively muddy. With soft doors simply lift the door off the Jeep, place it in the back and step out onto the front tire while clinging to the windshield. From there flop onto the hood and crawl to the front of the Jeep. Assume a sitting position on the hood with your feet on the bumper and try to either throw one end of your strap to someone standing at the edge of the mud or try to catch the end of theirs. If you happen to be on shore it may be fun to throw short the first time so the catcher has to grab the muddy end of the strap as it comes flying at them. Use common sense and don't throw a strap with a shackle or metal tow hook attached to it (better yet, Never even bring a strap with an attached tow hook to a trail ride - they are extremely dangerous).
The idea here has been to give you a few ideas to help you make it through with the minimum impact to the trail, your vehicle and yourself. These are general guidelines that often work, not hard and fast rules. Every vehicle and situation is different. Use common sense, and don't compromise safety. When in doubt winch it out.
Thanks to Lahore 4WD Club for the Info. ( Of which I was a member when I had a Jeep, not an active one though ).