Kumho said this in response to my email to them:
"Hi Michael
Sorry to hear that you had a bad experience with one of our products.
We do sell high quality well engineered products, and problems like this
are rare. Unfortunately though they do happen from time to time as a
result of all sorts of different factors. Be that manufacturing fault or
not. This can also be said of all other tyre brands.
You have clearly done the right thing in returning to your local dealer.
The retailer should send the tyre back to us for inspection. If we find a
manufacturing fault with the tyre, we will provide the dealer with an
allowance based on tread usage, this will then be passed back on to you.
I hope this helps.
Kind Regards
Dan Woodward
Brand Manager
Kumho Tyre (UK) Ltd"
So basically I will get some "
store credit" if they are found to be faulty, which they clearly are.