I´ve owned my C-90 for 3+ years. I´ve put 18K on the original tires and I swear they still look prety good;fair tread depth and uniform wear. My Question:what´s the general auerage amount of miles/time can you put on a tire before replacement? Is dry storage factored into the equation for tire replacement? i feel the tire´s got another 5-6k miles more...My riding buds say different.