I put on 4 Kumho 195R14 LR "D" tires back in mid 2013 which were about 12 to 18 mo old at the time. The load on each tire was close to 1700lbs and I typically ran themn at 60 to 65. The last Jan I had one go bad with tread separation and at the time had 6400 mi on it. I had to use my GY marathon spare and I purchased another matching GY Marathon tire on the existing rim and am now running 2 of the Kumho's on one side and GY Marathons on the other and have put another 2500 miles w/o issues since Jan. I bought another rim and I now carry a spare mounted Kumho and a spare mounted GY and plan to upgrade my existing configuration with Kumho 857s in the size 205R14 LR "D" at my next normal complete tire replacement. The only reason I'm running a mixed bag of tires now is the 195R14 LR "D" Kumho is no long available.
Even having one of the Kumhos go bad I still think that was just a luck of the draw. BTW previous to this tire separation with my current Kumhos I had run GY Marathons since 1995 with no tread separations and only one flat from a nail with about 75K total miles usage.
Something to consider IMO is running tires like the Kumhos or even Maxxis which are not normally available like the GY Marathons are one might be wise to carry two spares even if the second is not mounted so if you have one that goes bad on the road you can use a spare and still have another available until you can have time to replace the bad tire. I'm just leary of traveling very far from home w/o a spare for even a few hundred miles and about the only tire that is universally available like at WM or GY dealers nationwide are the GY Marathons since IMO they are the most used ST tire out there.
Larry