31x10.50R15 tire size

A 31x10.50R15 tire is 31 inches (787 mm) tall and 10.5 inches (267 mm) wide by its name, for a 15-inch wheel, so each sidewall is 8 inches (203 mm). It makes about 651 revolutions a mile.

Sources checked

Dimension31x10.50R15
Overall diameter31.00 in (787 mm)
Section width10.50 in (267 mm)
Sidewall height8.00 in (203 mm)
Aspect ratio76%
Rim diameter15 in
Circumference97.4 in (2,474 mm)
Revolutions per mile651
Revolutions per km404

Compare 31x10.50R15 with another size

Metric, LT and flotation

As printed on the sidewall: 265/70R17, LT285/75R16, 33x12.50R15.

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A 31x10.50R15LT tire is

31.0in tall787mm

on a 15-inch wheel

Width
10.50 in (267 mm)
Sidewall
8.00 in (203 mm)
Circumference
97.4 in
Revolutions per mile
651

31x10.50R15LT in full

Dimension31x10.50R15LT
Overall diameter31.00 in (787 mm)
Section width10.50 in (267 mm)
Sidewall height8.00 in (203 mm)
Aspect ratio76%
Rim diameter15 in
Circumference97.4 in
Revolutions per mile651
Revolutions per km404

The working

  1. 31x10.50R15LT: 31.00 in tall and 10.50 in wide, as the size says.
  2. Sidewall = (diameter − rim) ÷ 2 = (31 − 15) ÷ 2 = 8.00 in.
  3. Circumference = π × 31.00 = 97.4 in; revolutions per mile = 63,360 ÷ 97.4 = 651.

Where the 31x10.50R15 numbers come from

A flotation size names its height and width: 31 inches tall and 10.5 inches wide, on a 15-inch rim. Each sidewall is what’s left: (31 − 15) ÷ 2 = 8.00 inches, so the sidewall is 76% of the width.

One turn covers π × 31.00 = 97.4 inches, so the tire turns 651 times a mile and 404 times a kilometer.

What tire makers publish for 31x10.50R15

Inflated on the maker’s measuring rim. The percentage is the printed diameter against the 31.00 inches worked out above.

TireSize as printedDiameterWidthRevs per mile
Toyo Open Country A/T III31X10.50R15LT30.7 in (−1.0%)10.6 in676

Other 15-inch sizes against 31x10.50R15

Each size’s height against 31x10.50R15, and what a speedometer set for 31x10.50R15 shows at 60 mph with that size on.

SizeDiameterWidthHeight changeAt 60 mph shown
195/65R1525.0 in7.7 in−19.4%48.3 mph
205/65R1525.5 in8.1 in−17.8%49.3 mph
235/75R1528.9 in9.3 in−6.8%55.9 mph
33x12.50R1533.0 in12.5 in+6.5%63.9 mph

Every size: the tire size calculator. With the wheels off, the nuts go back on at your vehicle’s lug nut torque.

Questions

How tall is a 31x10.50R15 tire really?

31 inches by its name. Measured inflated, the makers’ tables on this page give 30.7 inches. Tread depth and the rim it’s measured on make the difference.

How many revolutions per mile does a 31x10.50R15 make?

651 by its diameter: 63,360 inches in a mile ÷ 97.4 inches a turn. Tire makers’ published figures are measured under load, when the tire rolls on a slightly smaller radius, and run 2.8% to 3.3% higher in Toyo’s tables.

Is 31x10.50R15 an LT tire?

Yes. Bridgestone’s guide describes flotation sizes as light-truck tires, written with LT after the rim: 31x10.50R15LT. They carry one load index, as they’re not made to run as duals.

Sources

  1. Bridgestone Americas: Determining tire size: P-metric, Euro-metric, LT-metric, C-type and flotation sizes, and what each number means (checked October 28, 2026)
  2. Toyo Tires: Extensa A/S II sizes and specifications: inflated overall diameter and width, revolutions per mile (checked October 28, 2026)
  3. Toyo Tires: Proxes Sport A/S sizes and specifications: inflated overall diameter and width, revolutions per mile (checked October 28, 2026)
  4. Toyo Tires: Open Country A/T III sizes and specifications: P-metric, LT-metric and flotation sizes, with revolutions per mile (checked October 28, 2026)
  5. Nitto Tire: Trail Grappler M/T sizes and specs: inflated overall diameter and width, LT-metric and flotation sizes (checked October 28, 2026)

Spotted a number that doesn’t match your manual or a source? Tell us; corrections are logged on the sources page.