Sticky tires are dirtier than they look

California’s proposed tire rules are not as silly as they sound

tires

California’s proposed replacement-tire rules are aimed at reducing rolling resistance, which is exactly the boring technical phrase that matters here. A tire that takes more energy to roll makes a gas car burn more fuel or an EV use more battery. Softer, stickier compounds can also wear faster, shedding more tire particles into the air, soil, and water. That is not “fun.” That is a consumable pollution source with a fan club.

As it stands, the legislation is clear: Tires that don’t meet the performance standard won’t be eligible for sale in California. There will be exemptions for tire models that sell fewer than 15,000 units a year, are ultra-high-treadwear (1,000 UTQG and above), are motorcycle tires, snow tires, and space-saver spares. That 15,000 number may be the saving grace of track day tires, though some models may outsell that number. Either way, it’s not looking great for ultra-grippy tires, though they represent such a tiny fraction of a bigger market that it shouldn’t be an issue for the average consumer.

But for the average enthusiast, most summer tires should land within California’s proposed rules, even if they’ll be considered inefficient. And these rules are only proposed, meaning they can be changed or even thrown out entirely. These rules are designed specifically for the commuting masses to protect average people from losing fuel efficiency over the lifetime of their vehicles. And of course, California wants to reduce overall emissions from tire particulates.

Motor1

The California Energy Commission’s proposed Replacement Tire Efficiency Program would set rolling-resistance standards for passenger-car and light-truck replacement tires. The goal is to make replacement tires as energy-efficient as original-equipment tires while also meeting a wet-grip safety standard. Lower rolling resistance means cars waste less energy.

This makes sense. A tire that takes more force to roll costs drivers money and burns more fuel. In EVs, it reduces range. And because tire wear is also a major source of particulate pollution, especially as vehicles get heavier, tire rules are a perfectly reasonable place for regulators to look.

No one wants to breathe tire dust.