What is SMR 20?
SMR 20 is a technically specified block natural rubber produced in Malaysia and graded by the Malaysian Rubber Board.
SMR stands for Standard Malaysian Rubber — a scheme under which natural rubber is graded by measured technical properties rather than visual appearance. SMR 20 is the most traded grade and the global benchmark for tire-grade natural rubber.
It is produced mainly from field coagulum and cup lump, then processed into ~33.3 kg or 35 kg bales. The number 20 refers to the specification class: dirt content must not exceed 0.16%, with limits also set for ash, nitrogen, volatile matter, initial plasticity (Po) and the Plasticity Retention Index (PRI).
Because it combines consistent quality with lower cost than latex-grade rubber, SMR 20 is used overwhelmingly in tire manufacturing, as well as in industrial rubber goods.