California is trying to regulate tire rolling resistance to reduce statewide fuel consumption, and it could limit enthusiast tire choices.

The California Energy Commission (CEC) wants to introduce a law that sets a minimum tire rolling resistance target to help save a claimed $1 billion in extra fuel costs experienced by drivers.

Basically, California is trying to set the performance standard for aftermarket tires, which can change almost everything, especially for enthusiasts who use inefficient but grippy high-performance tires.

the CEC wants all tires to meet or exceed the standards of Original Equipment (OE) tires, which are the tires that come with the car when it's brand new.

https://www.motor1.com/news/797503/california-tire-rolling-resistance-rules/