The set I'm using right now have lasted well over a year, including a tour of New Zealand's South Island, Mt Buggary, hundreds of commutes and numerous other rides -- totalling somewhere in the range of 20-25,000km. Fact.
The trouble is, the name of the manufacturer has long since worn off, so I'll just have to go on appearance when I replace them. 
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I am clinically insane. I am proud of it.
That is all.