40x12.50-17 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 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.

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.

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.

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

Both 38x13.50-17 and 40x13.50-17 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. 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 Fitment

A 40-inch tire - regardless of construction - demands substantial vehicle preparation:

• Major suspension lift, typically 4"+ minimum, depending on vehicle platform and wheel offset
• Fender cutting or flare extensions - factory fenders on most trucks and Jeeps will not clear a 40-inch tire
• Axle regearing to compensate for the 40-inch rolling diameter - 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
• Brake system review - the increased rotating mass raises braking distances and thermal load on brake components
• Wheel offset and backspacing planned for the 13.5-inch section width
• Drivetrain reinforcement evaluation - axle shafts, ring and pinion gears, and u-joints should be assessed for the increased torque load

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