Hi, I bought a 2008 Kawasaki Vulcan 500 LTD a year and half ago with 750 miles on it. It had been mostly stored and moved with a military couple. I have put over 5000 miles on it. Since the bike was stored in either moving crates or covered in a garage, I'm not sure about the tire life. They are Bridgestone tires, original, and don't appear to have any cracks on them. They ride ok and have tread. How many miles should I get out of these tires?