The trail rating system
I've run into a person or two who have been a little confused by the trail rating system that we all take for granted. It's a topic that can be slightly confusing, mainly because not everyone follows the same scale, and trail difficulty can be a very subjective topic. An "easy" trail to me, might be a nightmare to someone else. In order to level the playing field, and make sure that everyone can pick their trails on the same scale, we need a common set of ratings.
A good example of an organization that had to tackle this problem in a very big way would be the folks at Jeep Jamboree USA. Participants attending a Jeep Jamboree might be hitting the trails for the first time, and might have no real idea of what their vehicle is capable of. So a system of rating trails is very important. Because of that, I'm basing this article on their system.
They use a 1-10 scale, ten being the hardest. These numbers are then broken down into colors. Green, Blue, Yellow, Black, and Double Black. I'll break them down.
Green trails are usually just a step up from access roads. They should be fun, and slightly challenging for new off-roaders. Dirt roads, mud puddles, mild water crossings, small rocks, and wash-outs are what you can expect here. 4wd may be optional.
Blue trails are a step up from greens. Expect larger rocks, and tougher terrain. More driving skill is necessary, but a new driver in the right equipped vehicle shouldn't have too much trouble, with an experienced guide/spotter. 4wd high, and sometimes Low, will be required for blue trails.
Sometimes referred to as a "High Blue" yellow trails are a step between a blue and a black. More rocks, difficult terrain. At least one locker, and more use of 4-low is required here.
Black trails are usually for the experienced. A well equipped rig with a less eperienced driver behind the wheel, and a good guide, can complete a black trail, but you'll be in for a challenge. Minimum of one locker, and 4-low will be a must. Expect large boulders, your undercarriage will take some hits. Higher clearance and large tires are also very important.
The double-black, sometimes called a red, is as tough as they come. Lockers front and rear, large tires (35"+ minimum) and low gearing will be your friend here. Experienced drivers only, and a highly modified rig.