37x13.50-17 Tire Size

All You Need to Know About 37x13.50-17 Tires

A 37x13.50-17 tire is a wide flotation tire with a nominal 37-inch overall diameter, a 13.5-inch section width, and a 17-inch wheel diameter. The hyphen (-) in the size written as 37x13.50-17, not 37X13.50R17, identifies this as a non-radial (bias-ply) construction tire. That single formatting difference is the most important thing to understand about this size - it determines construction type, use case, and on-road behavior. For the radial version of this size, see the 37X13.50R17 article. For the Light Truck radial version, see 37X13.50R17LT.

37x13.50-17 Size Quick Specs

The table below lists the defining dimensions and fitment parameters for 37x13.50-17 as established by the TRA (Tire and Rim Association) flotation tire standards. Actual measured diameter will vary by brand and should always be verified against the manufacturer's published inflated dimensions before purchase.

Note on actual diameter: Like all flotation tires, 37x13.50-17 tires measure smaller than their stated nominal size when mounted and inflated. Actual diameter typically runs approximately 36.0"-36.5". Always check the manufacturer's published inflated diameter before purchase.

What 37x13.50-17 Means - Notation Explained

• 37 = nominal tire height in inches
• 13.50 = nominal tire width in inches
• -17 = 17-inch wheel diameter; the hyphen (not "R") confirms bias-ply construction

In the flotation tire sizing system, the letter "R" between the width and wheel diameter signals radial construction (such as in the 37x13.50R17 example). Its absence - replaced by a hyphen - means the tire is bias-ply. This is not interchangeable. A 37x13.50-17 tire and a 37X13.50R17 tire are the same nominal size but built differently: the bias-ply 37x13.50-17 uses diagonal cord plies (angled approximately 30-40 degrees to the centerline), while the radial 37X13.50R17 uses cords running perpendicular to the centerline. The difference determines flex behavior, heat buildup, and suitability for sustained highway speeds.

37x13.50-17 vs 37X13.50R17: Construction Comparison

Both 37x13.50-17  and 37x13.50R17 sizes share the same nominal diameter, width, and wheel diameter. The following table identifies the construction differences that determine which one is appropriate for a given vehicle and use case.

Where 37x13.50-17 Fits Best

37x13.50-17 bias-ply tires are a deliberate choice, not a default. Builders running rock crawlers, competition rigs, and serious sand vehicles select bias construction because the casing flexes and conforms over uneven surfaces in ways a radial casing resists. At low speeds on rough terrain, the bias-ply casing physically wraps around rocks and root systems, increasing contact area. Examples of purpose-built 37x13.50-17 bias-ply tires still actively sold include the Maxxis Trepador, which is DOT-approved and built specifically for this bias-ply off-road application.

The 37x13.50-17  size is not suited for daily highway driving. Bias-ply construction builds heat faster at sustained highway speeds due to the diagonal cord structure generating more flex per revolution. Increased heat buildup accelerates compound degradation, shortens tread life, and can cause structural failure at highway speeds - factors that do not apply to the radial 37X13.50R17 equivalent.

37x13.50-17 vs 37x12.50-17: Width Difference

Both 37x12.50-17 and 37x13.50-17 are bias-ply 37-inch flotation tires on 17-inch wheels. The only difference is the section width.

The 37x13.50-17 is one inch wider than a 37x12.50-17. The added width increases the tire's contact footprint, which on soft terrain (sand, loose dirt) distributes vehicle weight over a larger area and reduces sinkage. On built vehicles, the wider 13.5-inch section also increases the risk of rubbing against fender wells, inner liners, and suspension components at full lock or full droop. Wheel offset becomes a more critical variable with 13.5-inch-wide tires because the wider section extends further inboard and outboard than a 12.5-inch equivalent on the same backspace.

Pre-Installation Checklist for 37x13.50-17

Before fitting 37x13.50-17 tires, verify each of the following:

• Wheel width falls within the 9.0"-12.0" approved range for this size
• Lift height is adequate for 37-inch tire clearance at full suspension travel
• Fender and inner liner clearance accommodates the 13.5-inch section width - not just at rest, but through full steering lock and suspension articulation
• Steering lock clearance at full articulation has been physically checked, not just estimated
• Axle gearing has been evaluated to compensate for the 37-inch rolling diameter (a 37-inch tire has a circumference of approximately 116 inches, compared to ~107 inches for a 33-inch tire - this affects effective gear ratio and engine RPM at speed)
• Brake performance has been assessed for the increased unsprung and rotating weight
• Wheel offset and backspacing are appropriate for the 13.5-inch section width