Compound hardness determines normal tyre wear. Generally harder compounds wear the longest but have the least amount of road grip in the wet and slippery conditions. Soft compounds stick like poo to a blanket and give excellent grip in all conditions but wear rapidly.
If you want longer wear distances ask for harder compound tyres, not simply the ones you have now. If you are getting less wear then you most likely have very softer tyres. Its all really trade off and as in astronomy there is no one great tyre, each has it positives and of course negatives. Also some cars require softer compounds to track properly.
How do I know this? I spent a great deal of time and money on tyres in my youth which were attached to a LJ GTR XU1.
Erick you need to tell people the exact model tyre as Yokohama make both hard and soft compound tyres.
I am sure there are some people here that work in the tyre industry that would have far more knowledge on this subject.