12,000 miles is about right for those tires. Be happy you don't have the Dunlops. They are almost double the price. Went through 3 sets in under 40k miles on previous X5.

Non RF will definitely last longer if you decide to change.

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12 X5 50i Sport
06 Porsche Boxster S
08 X5 4.8i Sport (Sold)
06 Range Rover Sport SC (Sold)
03 330i Performance (Sold)
01 330ic (Sold)