If he had a rear tire BLOW out then he was running unsafe tires. Meaning that there was prob cords showing of close to it, never heard of a bike tire blowing out. Even if you pick up a screw, or nail it will not pop just leak out slowly. Hell a guy I work with pick up a piece of green rod steel in his back tire on the commute into work and his tire held, till after work when the air leaked out. Good thing this guy had gear on atleast he was smart about that.