'R' compound tyres are not what they used to be.
Twenty years ago I competed in the CSP class of SCCA AutoX with a 1800lb Honda CRX. A set of 13" Yokahama 008R tyres would last a season and then go on to do 20,000 miles on the street as the compound heat-cycled and hardened.
These 16" Kumho V700 tyres lasted only 2 AutoX's on my 2800lb MINI before one front tyre corded, and the other front tyre got tread separation. I really miss those Yokahama tyres.
In the photo you can see the line where the two ends of the tread are joined together during manufacture.