2009 Murano - Premature Tire Wear

[vcgjm1954]

Would anyone have an idea of why our 2009 Murano LE is having significant premature rear tire wear? The front tires wear normally, but we have had to replace two sets of rear tires since we bought it in 2013. No record of accidents. The rear tires of the last set of new Michelin Latitudes had to be replaced after just 14,000 km (almost exclusively highway driving). A Nissan dealership conducted a thorough inspection, but said they could find no reason for it. Help!!

[vcgjm1954]

I forgot to add that the rear tire wear is uniform across the entire face of the tires (not just inside or outside). The alignment has been double checked, hubs, camber etc has been checked with no apparent defects.