We have always heard that you should buy new tires for your motorhome/RV every 7 years regardless of the wear and tear. Ours are coming up on 7 years old but only have about 30,000 miles on them and look in good shape. Also when parked at home (which was an accumulated total of about 8 months each year) the tires have always been on concrete with tire covers on them, so we're wondering if those conditions could make a difference with the 7 years guideline. We don't want to take chances, but we would rather not replace tires that are still good. Do most of you follow the 7 years guideline?