Mud-terrain (MT) tires are specifically designed to perform off-road - on jagged rocks, loose soil, sticky mud or slippery sand. MT tires feature large tread blocks with wide, deep voids between them which allows for better traction on off-road surfaces. These voids also "spit" any mud, gravel and debris that might have accumulated as it spins, ensuring a clean tire surface for better grip.
Of course, MT tires also have their cons - they tend to be noisier, rough, and hard to balance. They've clumsy handling qualities especially on wet surfaces. Lastly, their bulky and heavy which translates to higher fuel consumption. If you’re using your 4x4 for a quick ride around town, that may not be too bad. But if you're going on a long trip, don't even think about it.
An All-terrain (AT) tire on the other hand, sacrifice a certain degree of off-road traction, with its smaller tread blocks, narrower tread voids and less-robust internal construction and tread compounds. The tread on AT tires are also permeated with sipes to ensure better road grip. This makes them a much better choice for driving in wet conditions. Though AT tires have poor off-road traction, they offer a smoother ride experience, reduced road noise level and better handling in most driving surface even in wet conditions. Except off-road, of course. But AT tires are perfect for epic road trips.
If you're into off-roading, chances are you’re going to be disappointed with AT tires. But they're a better choice, however, for all-around on and off pavement drives - back and forth to work, the store, travel, all the usual things you'd expect from a light truck or SUV.
But if you spend a lot of time playing in the mud, MT tires are best. Just be prepared for the downside - harsh ride, noise, increased fuel consumption, and poor drivability. But they sure look good ... *sigh.
Well, if you've cash to spare, you know what to do.