The tires, in size 205/45R17, will be supplied by Bridgestone Corp. in Japan.
The Bridgestone Potenza RE050A carries a UTQG rating of 140 for treadwear, A for traction and A for temperature.

(Akron/Tire Review) The Bridgestone Potenza RE050A run-flat has been tapped as an optional tire for the 2006 Mazda MX-5 Miata.
The tires, in size 205/45R17, will be supplied by Bridgestone Corp. in Japan.
The Bridgestone Potenza RE050A carries a UTQG rating of 140 for treadwear, A for traction and A for temperature.