I experienced the same thing with a Hutchinson Carbon Comp Tire.
I mounted it on several rims and with different tube and same result - Hump.
Faulty Tire IMO.
Doubt there is a blowout danger, but mine was irritating enough on a ride that I stopped using it and it kinda turned me off to Hutchinson Tires, although 1 bad tire is hardly a pattern.
It sounds like jmlapoint has tried a bunch of things to see if it really is a buldge or just a slighty off mounting job.
Make sure that you check those things first before ditching the tire. Is there an obvious lump on the sidewall or does it just seem to jump a bit when you spin it (im assuming its mounted). If it isnt the side wall, try deflating it, and making sure that the bead is sitting right. With some clinchers, like the tubeless mtb tires, they dont seem to just fit into place when you pump them up. If this is the case, it can be helpful to use a little soapy water on the tire to make it slip into place nicely just before pumping it up to pressure.
A buldge on a new tire wouldnt seem to be as high a risk for a blow out since the side walls, and or tread should still be pretty thick, but it is an irregularity, and may be a thin spot in the rubber. If the buldge is only evident when you pump it up, the risk is probably a lot greater since the tire is showing some fatigue under pressure. Dont ride it. If it is always there and doesnt change, you could probably get away with it if you dont mind the bumpy ride. Aside from complete blowouts, some buldges may make it a bit more likely to pinch the tube, depending on how big the buldge is.
It bugs me when you pay good money for stuff (tires arent cheap) and it isnt right. Ive had similar happen with cheaper tires before, and with expensive ultra light tubes by maxis before. Not the buldge, but the valve stem just fell off. it was really weird.
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