Part of the reason Coopers offer a big mileage warranty is because the tread depth is between 8MM and 10MM, where normal tyres are around the 6MM mark.
If the OP is running Coopers, did they come with their famous 60,000K mileage warranty for passenger tyres? (Might even be 80,000K)..Most of them do
Did you follow the schedule specified to keep the warranty...ie alignment when fitted and 10,000K after?
If you did, did you request a new set, with the costs reduced for the new set, that would be offset with the mileage you got from the last set? They guarantee, that if you fail to get the mileage specified and have followed their procedure, they work out the percentage cost based on what you used and take it off the price of a new set.
Ideal tyres for the application the ute is used is a light truck tyre, however to my knowledge there is no light truck tyre in a 225/60X16,which is the minimum diametre tyre that can be used on the ute..As for anything bigger,ie 17" + the same...Nothing in a light truck that can be fitted to the ute