Any tire experts out there? I've read that one should replace tires after 7 years regardless of wear,(due to sun, weather,road beating etc.) this sounds reasonable to me. My question is do you go by manufacture date or date of install? I just checked the tire manufacture date on my 2008 3585SA and it is 10/99. Going by the 7 year rule that means the tires were due for replacement even before they were put on the rig. Is there a shelf life to be figured into the 7 year rule? So far I haven't had the rig on the road but I plan on fulltiming in about a year and wondering if I should replace tires before starting out.