rubber is a natural product, over time it dries out and shrinks, the shrinking can cause cracking in the tyre grooves, these you might not see, another shrinking problem is the rubber becomes seperated from the carcass, sedate riding or not, delamination at any speed and you will be in for a shocker, had a set of continental tyers on mine when i bought it, 10 years stood still, the flat sopt on them was noticable, and the rear flung itself apart when i did a burn out in me garage, change them
