Firestone Duraforce RT 320/80R18 141B - 380497

Shop the Firestone Duraforce RT 320/80R18 at ThreePiece.us — free shipping on every order, Affirm financing available, and fast delivery nationwide.

What 320/80R18 means

In the size 320/80R18, 320 is the section width in millimeters (12.60 in), 80 is the aspect ratio — the sidewall stands 80% as tall as the tire is wide, or 256.0 mm (10.08 in) — R denotes radial construction, and 18 is the wheel diameter in inches. That works out to an overall diameter of about 38.16 inches, turning roughly 529 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 service description on this tire decodes to a load index of 141 — a maximum load of 5,677 lbs per tire.

Specifications

Frequently asked questions

How fast does this tire ship?

Every order at ThreePiece.us ships free, with fast delivery from a nationwide warehouse network. Affirm financing is available at checkout.

What does 141B mean on the Firestone Duraforce RT?

141B breaks down as load index 141 — rated for 5,677 lbs per tire.

Will 320/80R18 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 320/80R18, this tire matches your vehicle's fitment. If you're changing sizes, compare overall diameter to keep your speedometer and clearances right.

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