The JK tires with natural rubber are popular and work great. Before JK switched over mostly from the rubber they sold for years to the slightly different rubber they call L-Natural rubber. We still carry and sell both the L-Natural rubber and the batch before they offered the L rubber.
For prices check out the tire section at e-slotcar.com
Part number differences...
8711PP Older batch of rubber
8711PPL New batch of rubber
8711P Older batch
8711PPT Treated natural
8711PPW Wonder rubber
So if you want some of the tires that end in PP, now is a good time.
8711PP 3/32" x .765"
8701PP 3/32" x .765" with smaller hub than the 8711PP.
and many other sizes.