I got a pair of Blunder Thurts to try out, 650b x 2.1” for my gravel bike. No miles yet but some impressions from install. They seem to be a little looser than other tires I’ve mounted on the same wheels. If allowed to deflate, one of the tire beads will come off the shelf. Never had a problem with Vittoria or WTB tires I used on these rims (Astral Outback alloy rims). Hopefully this will resolve once the tire breaks in some and the casing relaxes.
The center knobs are pretty short and there aren’t many of them. I don’t expect the tire to last very long as a result.
Hopefully they ride really nice but unless I can get good mileage out of them it will be the last pair I buy.