CACC Rule Change Proposal
RCP-2026-6167

27.5.3 The dry spec tire for the CACC Spec Miata class will be the Toyo R or RR with tire size 205/50–
15.

27.5.3 The dry spec tire for the CACC Spec Miata class will be the Toyo R, RR or Hoosier RCES with tire size 205/50–
15.

Toyo replaced the previous Spec Miata tire with the Toyo R that has experienced numerous reported issues. The RR was subsequently brought back for one season after many complaints, but it has once again been discontinued. The issue with of R which has happened on numerous sets is the tread splitting across with width of the tire making the tire unsafe to use. Toyo's response has been buy a new tire which doesn't fit with local grassroots racer's budgets.
Hoosier has come out with the RCES which has been adopted as the spec tire for NASA Spec Miata which was developed to have increased durability and a consistent performance curve through the life of the tire which is similar to the Toyo RR.
Allowing both tires would allow a option should we see issues again with the Toyo Rs and have an option when tire shortages occur.