OK, 'Off-Road' tyres can be split into two catagories, tyres that are ILLEGAL for road use, becouse they dont meet the Construction & Use regulations, and tyres that are legal to use on the road, but aren't very good on tarmac. Think the Mitch Mil-specs are the latter, there are tyres like 'Swamp-Monsters' (I dont know the brand or marketing names, but you get the idea!) That are actually illegal for road use, becouse of teh construction and speed ratings etc, like Dumper-Truck or Tractor tyres.
You'll find that as a general rule the more off-road biased a tyre is, the deeper and more open the tread patern.
This means two things, first there is less rubber to tarmac contact area. Bigger the groves between the tread-blocks, smaller the tread-blocks, so for the same tyre size, less rubber in contact with tarmac.
Not such a BIG problem, as you can 'over-tyre' to some degree to compensate, and the physics of the thing 'self compensates' to some degree as the 'grip' you get is proportional to the pressure between road and rubber. Reduce the area of rubber, keep the weight over it the same you get more pressure, so more grip (per unit area).
Bigger problem is that the tread blocks are taller, so the bit of rubber in contact with the road is less well supported, so it can move about more, making the tread patern less stable, and you can get a phenominan known as 'tread creep' or 'tyre walk' where the treads sort of bend over a bit as you corner, so the tyre sort of creeps sideways as each tread-block comes round, touching the road behind the one informt that has twisted.
To combat this a bit, they tend to make off road tyres with bigger tread blocks so there is more rubber in each block, so more support, but they will still 'creep'.
However, means that there is a much bigger area of rubber between the relief grooves, so in the wet, what water is trapped between the tread block and the tar has further to travel being 'squeegeed' out into a groove, so they dont clear water as well as a full tarmac tyre with smaller treads and closer relief grooves, so dont offer the same amount of wet-road grip.
Again, there are some ways that they compensate, using softer compound rubber, being one, but that makes the treads even more liable to 'creep', and increases wear.
So overall it is a compromise between road manners and off-road grip, tyre life, cost, etc etc etc.
Simple answer to the Q, I THINK is the Mitch's are road legal, so you CAN use them on the road, but they are a noisy tyre, and they dont have the 'best' road manners; they will give less wet grip and they will make te handling a tad more 'wobbly', but I seem to recall that they are not SO bad, as they are classed as a high bias 'All-Terrain', they aren't a full 'mud' tyre.
