Originally Posted by BobbyG

Or you can wait until you experience catastrophic tire failure on a fast (really fast) downhill like I did many moons ago. On my MTB-based commuter with hybrid knobbies. Charging downhill at 35mph+ on a wide open MUP. BAM! It felt like David Beckham kicked my rear tire to the left. I seriously thought someone shot it out. Hit the brakes and slid like a dirt bike to the weed on the left which slowed me down to a stop. The sidewall had blown a seam just above the rim and the innertube had tried to squeeze out. My tire had looked like yours with some "cracks" for a few weeks prior. So besides the inconvenience of being stranded, you could loose control.