American Roadstar Sport AS 275/45R21

Looking for a 275/45R21 tire? The American Roadstar Sport AS is available now at ThreePiece.us with free shipping on every order and Affirm financing at checkout.

What 275/45R21 means

In the size 275/45R21, 275 is the section width in millimeters (10.83 in), 45 is the aspect ratio — the sidewall stands 45% as tall as the tire is wide, or 123.8 mm (4.87 in) — R denotes radial construction, and 21 is the wheel diameter in inches. That works out to an overall diameter of about 30.74 inches, turning roughly 656 revolutions per mile. Overall diameter is what matters for speedometer accuracy and clearance when you change sizes, so compare it — not just the width — against your current tire.

The manufacturer lists the overall diameter of this specific tire as 21 inches — when clearance is tight, go by the published figure rather than the nominal size math.

The service description on this tire decodes to a load index of 110 — a maximum load of 2,337 lbs per tire. The speed symbol Y corresponds to a maximum sustained speed of 186 mph.

Specifications

Frequently asked questions

What are the treadwear and warranty ratings on the American Roadstar Sport AS?

This tire carries a treadwear grade of 500, traction grade A, temperature grade A under UTQG.

Will 275/45R21 tires fit my vehicle?

Check the size molded into your current tire's sidewall or the tire placard inside the driver's door jamb — if it reads 275/45R21, this tire matches your vehicle's fitment. If you're changing sizes, compare overall diameter to keep your speedometer and clearances right. See every 275/45R21 tire in stock to compare options.

What does 110Y mean on the American Roadstar Sport AS?

110Y breaks down as load index 110 — rated for 2,337 lbs per tire — with a Y speed rating, good for a maximum sustained 186 mph.

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