Writing from England.
Some 3 years ago, I bought a set of 4 S1 Evo2 for my LS430. Two years later, they were found to to be cracking between the blocks - enough to earn me an advisory. I contacted Hankook, who said they will only investigate if I send them in (at my expense), and best-case, they will only refund in proportion to the depth of tread remaining. (Obviously this not practical for the average motorist - and they know this!)
Thinking that maybe it was just a bad batch, I ordered a replacement set of 4 for this year's MoT. And guess what? Half of them arrived out-of-round, i.e. oval-shaped! I kept the good pair, returned the bad for a refund, and ordered a new pair from a different supplier. And guess what? One of those two was oval, too! (So of course I rejected those and I'm still waiting to see what turns up next!)
So not only are there serious QC issues with their manufacturing and distribution, they make you jump through impossible hoops just to get any level of support. (Continental on the other hand, will send an agent out to you if you think you have a problem.)
Now, you might be wondering why I went for the same tyres a second time, seemingly not having learned. Well, they are (supposedly) the quietest out there in this size (245/45/R18), and they do seem to grip and handle pretty well. The wheel protection flange is a bonus, too.
But after this latest episode, I'm saying 'never again'!
Recommendation: Quality-control issues and a very high bar to get support.