I've got a 2013 Silverado 3500HD. The original OEM tires (Michelin LTX M/S2) have been great. I'm on my second set (114k on the odometer), and they still have tread, but we're full-time RV'ers and tow a very heavy 5th wheel. I'm ultra cautious about replacing tires before they have issues. The LTX's aren't made anymore, and the replacement tires I've heard about (Defenders) aren't made now, either. Does anyone know what the standard OEM tire on a new Silverado 3500HD is these days? All the Chevy website will say is "all-season highway". I believe the Michelin Agilis replaced the Defender/LTX. Thanks.