I've read of original equipment tires being done as soon as 20K miles but I'm not sure what people are getting out of the Duratrac tires specifically.
58,000 kms is not unrealistic for A/T tires without a warranty. For me 40K miles (~63,000 kms) is a good life for an A/T tire since it's a softer compound and designed more for off-pavement. You can get more or less depending on construction and intended use but that's what I would consider about average unless it carries a mileage warranty.
Many OE tires look like the ones you can buy at the tire shop but they are not. They are not constructed to the same standards as they are a bulk commercial order and most likely will not last as long as the "over the counter" versions you buy at full price. The TV you buy for 80% off on Black Friday looks the same on the outside but is not the same on the inside. Sony, LG, etc., are not losing as much money as you think for your great deal.
Since the Duratrac is only on the Rebel it could go either way since they are just on that model.