Cooper Discoverer S/T Maxx LT315/70R17/8 121/118Q - 170077004

The Cooper Discoverer S/T Maxx in 315/70R17 ships free from ThreePiece.us, with Affirm financing available at checkout and fast delivery from a nationwide warehouse network.

What 315/70R17 means

In the size 315/70R17, 315 is the section width in millimeters (12.40 in), 70 is the aspect ratio — the sidewall stands 70% as tall as the tire is wide, or 220.5 mm (8.68 in) — R denotes radial construction, and 17 is the wheel diameter in inches. That works out to an overall diameter of about 34.36 inches, turning roughly 587 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 34.57 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 121 — a maximum load of 3,197 lbs per tire, or 118 (2,910 lbs) per tire when mounted as duals. The speed symbol Q corresponds to a maximum sustained speed of 99 mph.

Specifications

Frequently asked questions

What does 121/118Q mean on the Cooper Discoverer S/T Maxx?

121/118Q breaks down as load index 121 — rated for 3,197 lbs per tire (118, or 2,910 lbs, in dual fitment) — with a Q speed rating, good for a maximum sustained 99 mph.

What kind of tire is the Cooper Discoverer S/T Maxx?

The Cooper Discoverer S/T Maxx in 315/70R17 is a all season tire.

Will 315/70R17 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 315/70R17, this tire matches your vehicle's fitment. If you're changing sizes, compare overall diameter to keep your speedometer and clearances right. See every 315/70R17 tire in stock to compare options.

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