Tire slips off the rim when inflated to 8bar I bought new wheels for my roadbike (shimano wh-rs80 which have c24 alu/carbon rims). I was mounting tires on them yesterday and inflated them to 8 bar (~116 psi). After a few moments (30 seconds or so), the tire started to slide off of the rim at a certain place, resulting in the inner tube to expand more than it could handle, and blow out.

I tried again with a new inner tube, checked that no part of the inner tube was stuck between the rim and the tire, inflated to 4 bar or so, checked again, inflated to 8 bar, BOOM. Same problem.

The tires are almost new continental GP4000s 23mm (a few 100 kms on a fulcrum 7 wheelset this summer) which were stored for a few months without using them. The inner tubes are also continental.

I checked the inside of the rim and can not see any damage or anything that looks odd. There is a factory installed rim tape in place, all brand new.

I had this twice with the front wheel and the same tire. I could try the rear wheel and/or the other tire to see if there is any difference, but I am a bit reluctant to potentially destroy yet another inner tube at this point.

Am I doing something wrong? Did I miss something given that these are new wheels?
Especially when seating a new tire for the first time (and probably more so on a "virgin" rim) it's wise to inflate to about 1/3 or 1/2 final pressure and then roll/bounce the wheel around quite a bit, to work the bead into position.  Then deflate, break the bead loose all around, and repeat the process.

Then, as you're doing the final inflation, watch the joint between tire and rim all around.  Usually there will be ribs in the side of the tire that should be a constant distance from the rim.  If you see the ribs moving up or down relative to the rim, stop inflating and manually work that section of tire back even.

Generally once the tire has been ridden a few miles it takes a "set" and will then reseat relatively easily if you have to repair the tube.

But do note that there are variations in tires and rims, some due to spec differences and some due to manufacturer differences.  It's possible in several scenarios to have a tire and rim that are simply not compatible.