I have recently dug my old generic mountain bike out from the depths of my garage, where it's been sat for the past 2 years.
Had to relube the chain, readjust the gears, etc, and got to the tyres. They both inflate and hold the air fine, but the tread rubber on the rear seems to have perished (the front is fine).
It was stored in a cool place, no extreme humidity, etc. Guessing the winter cold got to it (-15c here last winter!)
Is it safe to ride on it? The tyre seems sturdy enough, the tread doesnt have any weak spots and the tyre wall doesnt have any bulges.