Have Specialized Infinity tyres on our bikes - 70-100 psi. The tyres have a lot of tread and aren't worn, even though they are 3 years old, but one basically blew out while the bike was stationary. It hadn't been ridden for a week and the tyres were inflated at 80 psi. The tube blew a hole right through the kevlar (not sure of the spelling) lined tyres, resulting in a 5 cm diagonal rip in the tyre with fibre shreds poking out of the tear. Is this the usual thing to happen? (There were no foreign objects embedded in the tyre or the tube and the temperature on the day was around 30 deg C.)

Just curious as we have 3 more of these tyres yet to explode!