Just to add my other 2c worth,
When riding the TKC's on tar, these should be pumped up to 3 or 3.5 bar pressure. I also think that aging / curing of rubber has something to do with long life, so has heat cycling of tyres,
I feel that the stock of Germany TKC was hugh and these had time to stand on the rack. that is why we could get both and now only the Korean. I am going to buy a set and leave them under the workbench for 6 months, then fit them. See if this makes a difference.
Just my thoughts after reading some of the comments and statements.