40x13.50-17 Tire Size

All You Need to Know About 40x13.50-17 Tires

A 40x13.50-17 tire is a large flotation tire with a nominal 40-inch overall diameter, a 13.5-inch section width, and a 17-inch wheel diameter. The hyphenated format - 40x13.50-17, not 40X13.50R17 - identifies this as bias-ply (non-radial) construction. At 40 inches nominal diameter, this is a large tire that demands serious vehicle preparation regardless of construction type. The bias-ply variant is a deliberate choice for specific competition and low-speed extreme off-road applications; it is not the right choice for any vehicle that operates on pavement regularly. For the radial version of this size, see the 40X13.50R17 page. 

40x13.50-17 Size Quick Specs

The following specifications reflect the 40x13.50-17 size class. Actual dimensions should be confirmed with the manufacturer, as bias-ply tires at large diameters can vary more than radial equivalents.

Note on 40x13.50-17 actual diameter: All flotation tires measure smaller than their nominal stated size when mounted and inflated. A 40x13.50-17 tire typically runs 39.0"–39.8" in real-world diameter. Always confirm the manufacturer's published inflated diameter before purchase.

What 40x13.50-17 Means - Notation Explained

• 40 = nominal tire height in inches
• 13.50 = nominal tire width in inches
• -17 = 17-inch wheel diameter; the hyphen confirms bias-ply construction

The hyphen is the construction identifier. 40x13.50-17 is not the same as 40X13.50R17. The radial 40X13.50R17 is the far more common choice at this diameter - radial construction manages heat significantly better at highway speeds, and at 40-inch diameter, the difference in highway suitability between bias-ply and radial becomes pronounced. A 40x13.50-17 bias-ply tire should be treated as a purpose-built off-road or competition item, not a dual-purpose tire.

40x13.50-17 vs 40X13.50R17: Construction Comparison

Both 40x13.50-17 and 40X13.50R17 tires share the nominal 40-inch diameter, 13.5-inch section width, and 17-inch wheel fitment. The construction difference determines where each is appropriate:

For the radial version of this size, see 40X13.50R17. For the LT radial version, see 40X13.50R17LT.

40x13.50-17 vs 38x13.50-17: Height Comparison

Both 40x13.50-17 and 38x13.50-17 are bias-ply 13.5-inch-wide flotation tires on 17-inch wheels, differing only in nominal diameter.

The 40x13.50-17 adds approximately 2 inches of nominal diameter over the 38x13.50-17, translating to roughly 1 inch of additional axle clearance at the differential housing. The larger circumference (~125 inches versus ~119 inches for the 38-inch) produces a proportionally greater change in effective gear ratio — a 40-inch tire requires more aggressive regearing than the 38-inch to maintain equivalent drivability. Drivetrain stress, steering load, and braking demands all increase with the larger rotating mass.

40x13.50-17 vs 40X12.50R17: Width Comparison Within the 40-Inch Class

Both 40x13.50-17 and 40X12.50R17 tires share the 40-inch nominal diameter on a 17-inch wheel, but differ in section width and construction.

The 40x13.50-17 is one inch wider in section than the 40X12.50R17, and it is bias-ply rather than radial. These are not competing alternatives for the same buyer - the 40X12.50R17 is a radial street and trail tire, while the 40x13.50-17 is a bias-ply competition or dedicated off-road tire. The wider 13.5-inch section of the 40x13.50-17 increases the tire's contact footprint and terrain conformance at low speed, but also increases the fender and suspension clearance required.

40x13.50-17 Fitment Check

A 40-inch tire - regardless of construction - demands substantial vehicle preparation. For the 40x13.50-17 specifically, the combination of 40-inch diameter and 13.5-inch section width makes clearance planning more demanding than a narrower 40-inch option:

• Major suspension lift, typically 4"+ minimum, depending on vehicle platform and wheel offset - most Jeep and truck platforms require closer to 6" for adequate full-travel clearance at this diameter
• Fender cutting or flare extensions - factory fenders on virtually all trucks and Jeeps will not clear a 40-inch tire; the 13.5-inch section width extends further outboard than a 12.5-inch equivalent
• Axle regearing to compensate for the 40-inch rolling circumference (~125 inches) - most truck and Jeep platforms require a gear ratio of approximately 4.56 or lower
• Steering component upgrades - the larger tire diameter increases the mechanical load on tie rod ends, drag links, and steering boxes; bias-ply tires also transmit more feedback and shock through the steering at low speed due to the stiffer sidewall response under certain load conditions
• Brake system review - increased rotating mass raises braking distances and thermal load on rotors and pads
• Wheel offset and backspacing planned for the 13.5-inch section width - insufficient positive offset can allow the inner sidewall to contact the leaf spring or control arm
• Drivetrain reinforcement evaluation - axle shafts, ring and pinion gears, and u-joints should be assessed for the increased torque load that results from low gearing driving a 40-inch tire