Theres no need for R&D. Real rubber tyres are environmentally friendly as the abrasion particles are natural. They are much better performing in terms of grip, but just more expensivce to produce.
IIRC the military use real rubber tyres still because of their longer life and better performance.
If people were willing to pay more for their tyres then this would be a non issue.
Pure natural rubber has poor ozone resistance. It will need stabilizing additives, and at least one of these (6PPD) has been found to have toxicity problems.
If people were willing to pay more for their tyres then this would be a non issue.