37X12.50R17 Tire Size

All You Need to Know About 37X12.50R17 Tires

A 37X12.50R17 tire is a radial-construction flotation tire with a nominal 37-inch overall diameter, a 12.5-inch section width, and a 17-inch wheel diameter. The "R" in 37X12.50R17 explicitly confirms radial construction, which distinguishes this size from the non-radial 37x12.50-17 category. The 37X12.50R17 is the dominant modern format for 37-inch flotation tires and covers the majority of lifted truck, Jeep, and overland tire production in this diameter.

37X12.50R17 Size Quick Specs

• Nominal overall diameter: ~37 inches (actual mounted diameter varies by brand and load range)
• Nominal section width: ~12.5 inches
• Construction: Radial (R)
• Wheel diameter: 17 inches
• Recommended wheel width range: 8.5-11.0 inches
• Standard measuring rim: 17x10
• Available service types: Standard (P-metric equivalent) and LT - see 37X12.50R17LT for LT-specific information

Recommended 37x12.50R17 Tires

What 37X12.50R17 Means

• 37 = nominal tire diameter in inches
• X = flotation size format separator
• 12.50 = nominal section width in inches
• R = radial construction
• 17 = wheel diameter in inches

The "R" in 37X12.50R17 is not interchangeable with the non-R 37x12.50-17 designation. Radial construction in a 37X12.50R17 tire means the casing plies run perpendicular to the direction of travel, with circumferential steel belts stabilizing the tread. This architecture allows a 37X12.50R17 tire to run at sustained highway speeds with controlled heat buildup - a behavior that bias-ply 37x12.50-17 tires are not engineered to replicate.

Why Radial Construction Matters in 37X12.50R17

The radial construction in 37X12.50R17 tires produces measurable performance differences compared with bias-ply 37x12.50-17 construction:

• Highway tracking: The steel belt package in a 37X12.50R17 stabilizes tread contact at highway speeds; bias-ply casings in 37x12.50-17 tires tend to wander under the same conditions.
• Heat management: A 37X12.50R17 dissipates heat more efficiently at sustained speed, enabling highway use that would degrade a bias-ply 37x12.50-17 casing.
• Tread life: 37X12.50R17 radial tires consistently deliver longer tread life than bias-ply 37x12.50-17 alternatives under mixed on/off-road use.
• Ride quality: The independent tread and sidewall flex zones in a 37X12.50R17 produce a more compliant on-road ride than the stiffer bias-ply 37x12.50-17 casing.
• Wet-road behavior: 37X12.50R17 tires maintain more consistent tread contact on wet pavement than bias-ply 37x12.50-17 designs.

37X12.50R17 (Metric) Equivalents

Flotation sizes do not convert precisely into metric sizing. The closest metric radial alternatives to 37X12.50R17 are:

The 315/80R17 is the most commonly cited metric equivalent to the 37X12.50R17 because its diameter and width are closest. However, 315/80R17 and 37X12.50R17 are not interchangeable without confirming load index, speed rating, and vehicle clearance for both sizes. The 325/80R17 runs slightly taller and wider than the 37X12.50R17 and may not fit applications where the 37X12.50R17 is already at the fitment limit.

37X12.50R17 vs 37X13.50R17

The 37X12.50R17 and 37X13.50R17 share the same 37-inch nominal diameter. The 37X13.50R17's one additional inch of section width produces a larger tread contact patch, which can improve traction on loose surfaces. The narrower 37X12.50R17 fits a wider range of vehicles without fender contact, produces less steering effort at low speeds, and is more commonly available across tire brands. For vehicles where fitment is borderline or steering geometry is sensitive, the 37X12.50R17 is the lower-risk choice.

Clearance and Fitment for 37X12.50R17

Fitment requirements for a 37X12.50R17 are driven primarily by the tire's 37-inch diameter, not its 12.5-inch width. Most truck and Jeep platforms require a minimum 4-6 inch suspension lift to clear a 37X12.50R17 at full suspension travel. Fender trimming, inner liner removal, and bump-stop modification are common. Wheel offset and backspacing selection affect how the 37X12.50R17's 12.5-inch section width sits relative to the suspension components and fender edge.

Drivetrain Effects of Running 37X12.50R17

A 37X12.50R17 tire's approximately 116-inch rolling circumference increases drivetrain load relative to factory tire sizes. On vehicles where a 37X12.50R17 represents a significant diameter increase over the stock tire, the effective axle ratio drops, reducing acceleration, altering shift behavior in automatic transmissions, and increasing mechanical stress on axle and transfer case components. Re-gearing is common practice on builds running 37X12.50R17 tires. The specific re-gear ratio depends on the vehicle's original axle ratio and the diameter of its factory tire.