Ozoner
CRC's foam tire tutorial under their TECH DOWNLOADS is about the most comprehensive
on Trinity's site they list their own TRC tires with shore ratings
i haven't seen any comparison between TRC and Jaco/CRC compounds for 12th scale.
i have raced both and can tell you TRC purples are different than Jaco/CRC purple,s and that goes for greys, pinks, etc.........