My experience has been that OEM tires do not last nearly as long as replacement tires, even if the replacement tires are exactly the same brand, model, and size as the OEM tires you are replacing. Only got about 35,000 on OEM Bridgestones on last Expedition, and a little over 40,000 on OEM Michelins on current F350. Have used Michelin replacements on most vehicles and never a sidewall checking issue.
Truth or myth, have read that OEM tires are slightly different than exact replacements (slightly different compound and/or "shaved") to maximize new vehicle mpg.