Well what if the Triple Intervention suggested to British policy makers that a French - German - Russian alliance was possible? As such an alliance could plausibly destroy the British Empire, such a threat would need to be removed and an alliance with France and Russia might seem a reasonable...
On the subject of rubber, I found online long ago (2011) a table claiming to give the "Natural Rubber Production per country 1936-1948" referencing BR Mitchell as the source. This was possibly "International Historical Statistics"...