SUV's/4x4's have three categories of tyres that can yield varying characteristics.
Highway Terrain (HT) (90% on-road/10% off-road): These tyres tend to have 'rib' designed into the pattern to reduce noise, and also tend to provide longer life to the tyres as the pattern is less aggressive.
All Terrain (AT) (50% on-road/50% off-road): The most versatile of all SUV/4x4 tyres, a more aggressive pattern than highway tyres, but not as noisy and high wearing as the mud tyres. A great compromise on drivers that are on-road during the week, but occasionally take the vehicle off-road on the weekends.
Mud Terrain (MT) (10% on-road/90% off-road): The most aggressive pattern out of the three options, these are specifically designed for off-road capabilities, however some premium brands offer a tyre that can still suffice as a road tyre as well. All mud tyres will be noisy on-road, and will wear very quickly if the primacy use is on tarmac.