I was just riding along recently, descending Stunt Road in the Santa Monica Mountains, when I started to detect a slight hopping in my rear wheel. As I was on a fast descent with curves, I didn't want to risk my rear wheel sliding out, so I stopped to check it out. Imagine my shock when I saw bubbles between my tyre tread and the tyre casing, something I have never seen in my 31-year cycling career! I could tell there was nothing I could do about it, so I kept on descending, albeit more slowly.
The hopping soon became almost unrideable, so I stopped again after a quarter-mile. At this point, the "tumors" were really large, as you can see in the photos below.
I always carry a spare tyre when I ride an event, but not when just out riding in my home turf, so swapping out the tyre wasn't an option. I always carry several Park Tool tyre boots, but those weren't going to help, so I decided to just coast along and get closer to home before the inevitable happened and I had to call for a ride or hitch-hike.
But then, not only did my tyre not blow up, but all the tumors miraculously disappeared! Yep, just riding along, the ride became smooth. At the next stop sign, at the intersection of Stunt Road and Mulholland, I looked at my back tyre and there was no sign whatsoever that this crazy circumstance had unfolded. If I hadn't photographed my tyre, I would have almost thought I had been hallucinating.
I finished my ride without incident, but then the next day my back tyre was half-flat, suffering from a slow leak. Coincidence, or related? I will never know.
The tyres in question are my all-time favorite, best riding, best performing: Challenge Paris-Roubaix, 27mm wide. I love these tyres and will definitely continue to ride them (new ones). In this particular case, perhaps an issue was the age of the tyres. They were originally installed by Velo Cult on my Raleigh in January of 2011, but after a few rides I parked that bike for a few years. Recently I reconfigured the Raleigh and put the tyres on my Rivendell Roadeo instead. Therefore, though the tread was essentially new, the tyres themselves are at least three years old. Perhaps that's a factor?