60,000 on the rears is a very doable #...heck the same on the fronts would be great. Firstly there's not anyone poster on this site that I've encountered that has enough knowledge to comment on retreads, or as the industry now likes to be known as in the Remanufacture classification.
To with only buy retreads from the source manufacturer, not a 2nd or 3rd party. There are many that produce by the numbers not by the quality, most that is.
If you can't find a source check with the NTDRA(National Tire Dealers and Retreaders Association) for the nearest retreader.
If done right a retread should perform well enough to make the purchase worthwhile.