I'm in the same situation. I got a 700x23C Kenda K177 from
CRC yesterday. I'm not a
complete newb and have had to replace p****ered tubes, recently, at the roadside before - with this bike. Never had this problem before though.
First time I took it up to 100psi and a minute after refitting it to the bike realised the wheel wouldn't rotate. I saw the tyre had slipped off the rim and was only now being stopped by the presence of the chainstay. I deflated it and removed the wheel.
I didn't rotate the tyre in relation to the wheel, reinflated to about 50 psi, checked everything seated. Refitted to bike. inflated to 70. took for a 20 meter gentle ride. inflated to 100. I then wateched the tyre slowly bulge off the rim......
same position about 30 degrees from the valve.
What I have noticed is the clincher on the kenda doesn't seem to be as pronounced a feature as on the previous hutchinson tyre?
I'm tempted to get out some chalk to get reference positions on rim and tyre. Rotate the tyre on the rim and then go again. Essentially to sus if it's definitely the tyre as opposed to the rim. Only thing is, in the back of my mind I'm wondering "what if I'm 10 miles from home and I have to change the tube - will I get the same problem?"
As you have to pay the postage back to CRC(?) its hardly worth my bothering. If I prove it is the tyre I might as well bin it and fork out for something more expensive..
I'm going to keep following this thread, see if there's any more suggestions