How to Choose Tires for Autocross

Tires are the single biggest performance variable at an autocross event. The difference between a set of all-seasons and a set of 200-treadwear summer tires on the same car is measured in full seconds per run, not tenths. But autocross tire selection is not as simple as buying the grippiest thing that fits. Class rules, treadwear ratings, compound behavior, and sizing all factor into the decision.

Understanding Treadwear Ratings

The UTQG treadwear number stamped on every tire's sidewall is the most important number for autocross. It tells you roughly how fast the tire wears relative to a reference compound, and it determines which classes you can compete in.

Lower treadwear means softer rubber that grips harder. A 200tw tire will grip significantly more than one rated at 400. The tradeoff is wear: a 200tw tire used exclusively for autocross might last two to three seasons, while the same tire driven daily might last 15,000 to 25,000 miles. Ratings are self-reported by manufacturers, so there is some variation between brands, but as a category guide the number is reliable.

Autocross Tire Categories by Class

Street Class: 200 Treadwear and Above

SCCA Street class rules require tires rated 200tw or higher. This is where most competitors start because it allows serious performance rubber while keeping costs reasonable. The dominant tires here are the Bridgestone Potenza RE-71RS, Continental ExtremeContact Force, Falken Azenis RT660, and Yokohama Advan Apex V601.

The difference between these top-tier 200tw tires and a mid-grade all-season is enormous. On a typical 60-second course, the tire change alone can be worth 2 to 4 seconds. For someone running their first season, a set of 200tw tires on a second set of wheels is the ideal setup. Drive to the event on daily tires, swap in the paddock, and swap back when you leave.

Street Touring: 200 Treadwear Minimum

Street Touring also requires 200tw minimum but allows wider tires and more modifications. The tire selection is the same, but competitors pair it with aggressive alignment, wider-than-stock wheels, and more negative camber to extract every bit of grip. Tire width matters more here. Going from 225 to 245 or from 245 to 265 adds meaningful contact patch at the limit. Check your class rules for maximum width and match your wheel width to the tire for an optimal contact patch shape.

Extreme and Prepared: R-Compound Territory

Beyond street-class rules, R-compound tires enter the picture. These are semi-slick or full-slick competition tires with treadwear ratings below 200, often in the 40 to 100 range. Hoosier A7, BFGoodrich Rival S 1.5, and Toyo Proxes RR are the names you hear in paddock conversations.

R-compounds operate on a different level. The grip ceiling is dramatically higher, but they work best at specific operating temperatures. Cold R-compounds can feel greasy until they build heat. They are expensive ($250 to $350 per tire), they wear fast, they are terrible in rain, and they are not practical for street driving. For experienced competitors chasing trophies, they are worth it. For a first-year autocrosser, they are overkill.

How Compound Affects Grip and Wear

Softer compounds conform to pavement texture better, creating more mechanical grip. In autocross, this means more progressive breakaway at the limit. Instead of snapping from grip to slide, a softer tire transitions gradually, making the car more predictable at the edge. Harder compounds have a more abrupt transition with less warning.

Heat cycling affects compound over time. Every cycle from cold to operating temperature and back hardens the rubber slightly. A brand-new 200tw tire grips differently than the same tire 15 heat cycles later. For most local competitors, this is not worth obsessing over. Run the tires until they stop performing or the tread is gone. If you chase national-level times, tire management becomes part of the strategy.

Size: Width, Diameter, and Sidewall

Wider tires put more rubber on the ground, which generally means more grip. But there are practical limits. The tire needs to fit your wheel width correctly. A common autocross setup is one size wider than stock on wheels 0.5 to 1 inch wider. If your car came with 225/45R17 on 7.5-inch wheels, a 245/40R17 on 8-inch wheels is a proven step up.

Do not go overboard with width. On a 2,800-pound car making 180 horsepower, 275-width tires are unnecessary. The car does not generate enough force to use all that rubber. Match the tire to the car.

Lower-profile sidewalls mean less flex under load, which gives sharper turn-in. Higher profiles absorb bumps better. For autocross on smooth parking lots, lower profile usually wins. For rallycross or rough surfaces, sidewall compliance helps. If your car sees both, stick with whatever tire pressure and sizing works best for your primary surface.

Buying Advice for Your First Set

Pick a well-reviewed 200tw tire in a size that fits your stock wheels or a reasonably priced second set. Do not agonize over whether the RE-71RS is 0.2 seconds faster than the ExtremeContact Force. At the beginner level, driver improvement outweighs any difference between top-tier 200tw tires by a wide margin.

Compare autocross tire selection by size, treadwear, and price before committing. Prices vary significantly between retailers, and the same tire can be $20 to $40 cheaper per corner depending on where you buy.

Start with one set, run it for a season, and learn what the tire tells you. Outside edges wearing faster than the center means you need more negative camber or less pressure. Center wearing faster means too much pressure. Tire choice is one part of a larger autocross prep strategy. Get the tires right, handle the rest of the basics, and the times will come down.