40X13.50R17 Tire Size

All You Need to Know About 40X13.50R17 Tires

A 40X13.50R17 tire is a large radial flotation tire with a nominal 40-inch overall diameter, a 13.5-inch section width, radial construction ("R"), and a 17-inch wheel diameter. It is three inches taller in nominal diameter than the 37X13.50R17 and two inches taller than the 38X13.50R17, and represents a significant step up in vehicle preparation requirements from either of those sizes.

40X13.50R17 Size Quick Specs

The following specifications reflect the 40X13.50R17 size class. Actual inflated diameters vary by model - confirmed published diameters from specific tires are noted where available.

What 40X13.50R17 Means - Notation Explained

• 40 = nominal tire height in inches
• 13.50 = nominal tire width in inches
• R = radial construction
• 17 = wheel diameter in inches

40X13.50R17 Load Ranges Available

Unlike some sizes where only one or two load ranges are produced, 40X13.50R17 is available in Load Range C, D, and E from different manufacturers. The table below summarizes the load range options with representative tire models and load data:

40X13.50R17 load capacity note: Figures above are representative; actual values vary by specific tire model. Always use the specific tire's published load/inflation table for load planning. Load Range C figures shown are from the Toyo Open Country M/T published spec for 40X13.50R17.

Load range choice for 40X13.50R17 depends on the vehicle's gross vehicle weight, payload, and use case. Load Range C tires are common on lighter Jeep-based platforms running the 40-inch size. Load Range D and E are appropriate for heavy trucks, diesel builds, and vehicles carrying a significant payload or towing.

40X13.50R17 vs 37X13.50R17: Height Difference

Both 40X13.50R17 and 37X13.50R17 are radial 13.5-inch-wide flotation tires on 17-inch wheels. The 40X13.50R17 is three inches taller in nominal diameter than the 37X13.50R17 - approximately 1.5 inches of additional clearance at the axle housing. The 40-inch tire's larger circumference (~125.6" vs ~116" for a 37-inch) reduces the effective gear ratio: a vehicle running 3.73 axle gears with 37-inch tires would effectively operate as if it had approximately 4.03 gears after stepping to 40-inch tires. Most platforms require regearing to restore acceptable drivability and fuel efficiency. The following table shows the dimensional relationship:

For the bias-ply version of this size, see 40x13.50-17. For the LT-designated version, see 40X13.50R17LT.

Fitment Requirements for 40X13.50R17

Running 40X13.50R17 typically requires the following vehicle modifications:

• 4"–6"+ suspension lift, depending on platform - factory-height vehicles cannot accommodate a 40-inch tire
• Fender cutting or aftermarket flares - the 40-inch diameter and 13.5-inch width will contact factory fender openings on virtually all platforms
• Regearing, typically to 4.56 or lower for most truck and Jeep platforms, to compensate for the 40-inch rolling circumference
• Steering upgrades - the 40-inch diameter increases the mechanical load at tie rod ends, drag links, and the steering box
• Brake evaluation - increased unsprung and rotating mass raises braking distances and thermal demands on rotors and pads
• Wheel offset and backspacing planned for the 13.5-inch section width - insufficient clearance on the inboard side causes sidewall contact with the leaf spring or control arm
• Bump-stop modifications - even if the tire clears at ride height, it can contact the fender or inner liner at full suspension compression.