Best tyre choice for high mileage to save money?

I recently upgraded my 1997 BMW 528i alloys to M6 replica's which I bought from ebay with tyres but only got 10k out of the rear tyres driving sensibly. How can you tell which tyre gives the most miles between tyre changes? Is there an industry average indicator? Completely confused because I thought the average tyre got minimum 25k to 35k miles between changes when driven sensibly. As much information as possible please. Thanks.