I need 245/70/19.5 tires for our 26 foot Intent. It currently has GoodYear 670 on it, and they have been great, but no longer available. Apparently they were designed for RV use, with extra UV and Ozone protection. All I see available are truck, not RV tires. I am considering Good Year 647, or Hankook Smartflex H35. Any experience with these? What else should I look at? I would like tires that last a while.