So I had Continental Grand Prix 4000’s installed on my bike, and I have no idea how many miles it has, but it does have a few. I rode on the same pair on the Big Basin ride … all 78 miles and 7000+ feet of climbing on it. Then, I took it for a ride up King’s Mountain, and I descended down Hwy 35 northbound towards 92. Just before getting to 92, I felt the ride get a little bumpy. My first thought was flat, but after checking, it was no flat. So I continued on.
Later, while on Canada Rd, it was just bugging the hell out of me … so I inspected it further, and the tire does have a lateral bump on it.
I inspected the tire, and couldn’t find anything out of the ordinary. Tread was not worn down precariously, and there were no punctures … and the wheel is true, so it’s not like there’s a big dent in the rim. Oh well … gotta shell out for a new pair of tires. I guess it’s time.
Sevencyclist's Blog 
Wow, that’s a pretty bad bump or whatever it is. Get rid of it before something drastic happens.