New high quality tire doesn't sit evenly on the rim

Pump up the tire more until it seats itself properly on the rim. Deflate to desired pressure afterwards.

Make sure the tire is properly seated and the tube is not pinched anywhere. Then pump up to maximum allowed pressure (or even slightly higher). If the tube is pinched anywhere it will rupture with a very loud bang. If you are unsure, better wear some hearing protection or do it outside and keep as much distance to your head as possible.

Deflate to desired pressure afterwards.

Sometimes it’s actually the reflective stripe which is misaligned.

Sometimes I've found that pumping up the tyre to the rated pressure (or a little over), deflating most of the way, and pumping up again does the trick. You can chuck some water on the bead while its deflated (I use plain rather than soapy water for that; it's not as effective but doesn't leave a slippery residue)

You can also try riding a few hundred metres gently with the tyre fairly soft then pumping up hard.

A pump with a pressure gauge is really useful for stubborn tyres, I run mainly Schwalbe, and some of theirs can be tricky, though I've had worse.

Not sure if this helps, but I've had this exact same problem seating some schwalbe g-ones. They were tubeless tyres and I'd put tubes in them.

It didn't matter what i did, and I basically followed all of the above suggestions, they'd never seat properly.

The moment I removed the tubes and ran them tubeless they seated perfectly, clicked into the rims @ about 80 psi and I've never had any subsequent issues with them. The issue appeared at a random point just as yours have.

I have a sneaking suspicion that it was that the tubes put pressure on the wrong part of the tyre as its inflated. So my suggestion is that you try with a different diameter tube. I'm not sure if it should be larger or smaller, but give it a go with one you have handy.

Hope this helps.

When I fitted a new Schwalbe Marathon Plus, it kept bulging near the valve when I tried to inflate it. The solution was to replace the inner tube with a smaller one. I also discovered that the trick to getting the tyre on is to secure it with cords or cable ties as you work around, to stop one side slipping off. Edit: Thanks to the guys who suggested this in their responses.

Dont rule out the RIM Tape. I was led to this post because I was having problems mounting some 30mm and 32mm tyres on a front rim. I ruined the first tyre being a little too aggressive. When I had the same problem with the second tyre I started to wonder if there was a problem with the rim itself.

Did the soap, did the higher than recommended pressure...still no luck. Looking closer at the wheel after taking the tyre off I wondered if the fabric rim tape that was used could have been my problem. Replaced the fabric rim take with some of that yellow plastic tape rim tape and on my next attempt the tyre seated perfectly.

The rim in question was shallow and I think there was just enough friction with teh fabric tape to prevent the bead moving to the edge.

Shame about the first ruined tyre but I am happy that I got this seated on the second tyre.