Summer compound really ain't gonna last more than 15k on average...
I had my Diamaris brand new in February...I put 18k miles since then...the rears need replacement, fronts can go another 2-3k...but at over 1500$ a set,you might be better off with all seasons (although there's no comparison to the way the car handles on summer tires)
I've heard good things about the new Vredesteins, but also good things about made in Cheena ones(400$ set)lol
It's up to your budget , really....
I might go with some Pirelli's when I change mine...

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2006 X5 4.8is LeMans Blue / creambeige interior
Prod.date: 2006-06-21