How many miles can one expect to get out of a michelin tire . I'm old and don't drive fast anymore nor do i spin when i take off. I put a set of michelins on in november, hve driven about 4000 miles and today the wire is showing in the center of the rear tires. The front tires look like they are new. I had an alignment done as soon as the new tires were installed. Any body got any ideas. ??