38X11.50R17 Tire Size

All You Need to Know About 38X11.50R17 Tires

A 38X11.50R17 is a radial flotation tire combining an approximate 38-inch overall diameter with an 11.5-inch section width and a 17-inch wheel diameter. The "R" designates radial construction.

Critical availability note: Like its hyphenated counterpart, the 38X11.50R17 in radial form is extremely rare in mainstream production catalogs. Current 38-inch radial tires from major brands are predominantly produced in wider sections - most commonly 38X13.50R17 and 38X15.50R17. Buyers should independently verify current availability before planning a build around this specific size. The radial 38-inch narrow-width category is effectively a custom or near-custom tire market.

38X11.50R17 Size Quick Specs

What 38X11.50R17 Means

• 38 = approximate overall tire diameter in inches
• 11.50 = approximate section width in inches
• R = radial construction
• 17 = wheel diameter in inches

Why Radial Construction Becomes More Important at 38 Inches

As the 38X11.50R17's diameter pushes beyond the 37-inch threshold, the thermal and structural demands on the casing intensify - particularly on the highway segments that are part of most vehicle usage cycles. Radial construction addresses this through:

• Better heat dissipation from the 38X11.50R17 casing during sustained highway speeds
• More consistent tread contact patch shape across the 11.50-inch section width
• Improved tread wear distribution
• Greater sidewall compliance that reduces shock transmission to the wheel and axle

These advantages become increasingly relevant when running the 38X11.50R17 on any vehicle that mixes trail use with regular road miles.

38X11.50R17 vs 40X12.50R17

Moving from 38X11.50R17 to 40X12.50R17 adds approximately 1 inch of additional axle clearance - and simultaneously increases section width by 1 inch, compounding the fender and steering clearance demands already present with the 38X11.50R17. The 40X12.50R17 also requires a further axle gearing recalculation on top of whatever re-gearing the 38X11.50R17 already necessitated.

Both sizes sit firmly in extreme-fitment territory and are unsuitable for stock or mildly modified vehicles - but the 40X12.50R17 raises the modification threshold in both diameter and width simultaneously, making the 38X11.50R17 the more manageable option for builders not yet committed to a full competition-level build.

What to Check Before Installing 38X11.50R17 Tires

At 38 inches of diameter, the 38X11.50R17's clearance demands are dominated by height rather than width:

• Suspension lift: 5–6+ inches typically required to clear the 38X11.50R17 without fender contact (vehicle-dependent); 
• Axle gearing: significant gear ratio recalculation recommended; running the 38X11.50R17 on gears designed for 33-inch tires produces roughly an 11-15% effective ratio loss
• Steering clearance: full lock articulation clearance must be verified with the 38X11.50R17 mounted, not estimated from the unmounted tire dimension
• Wheel offset: corrected backspacing may be needed to keep the 38X11.50R17 clear of suspension components throughout the full range of articulation
• Brake system: the 38X11.50R17's larger diameter increases the lever arm at the wheel and can affect braking feel and pedal response; verify brake caliper clearance with the new wheel and tire combination installed
• Fender structure: most stock fenders require trimming or full replacement with tube flares to accommodate the 38X11.50R17's diameter.