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Tire sizes

245/60R20 — the narrow 20 on full-size trucks and SUVs

A 20-inch wheel package sized to roll exactly as far as the 17 and 18-inch packages it sits alongside.

Metric notation · Crossover and SUV

Overall diameter
31.57 in
802 mm
Section width
9.65 in
245 mm
Sidewall height
5.79 in
147 mm
Aspect ratio
60%
sidewall as a share of width
Wheel diameter
20 in
the hole in the middle
Circumference
99.2 in
2520 mm
Revolutions per mile
638.7
geometric, not measured
Revolutions per km
396.9
geometric, not measured
Typical load index
98–116
1653–2756 lb per tire

Crossovers are heavier than the cars they share size families with, so the same nominal size is produced at a higher index for SUV fitment than for passenger fitment. Two tires wearing the same size code can carry materially different loads.

The load-index range shown is the band this CLASS of size is typically produced in — not a list of what is in stock for this exact size today. Load index and speed symbol are printed on the sidewall of the specific tire you are holding, and the required minimum is on the placard of the specific vehicle you are fitting. Read both.

Nearest real sizes in imperial notation, same wheel

  • 33x12.50R2033.00 in tall+1.43 in
  • 35x12.50R2035.00 in tall+3.43 in
  • 37x12.50R2037.00 in tall+5.43 in

Compare any two sizes, including ones this site has no page for, in the comparison tool.

Platforms recorded with this size

Half-ton pickups and full-size SUVs offer this size on their larger factory wheels. At 9.65 in of section it is narrow for a 20-inch fitment, which is deliberate: the width is set by the vehicle, not by the wheel.

One vehicle, three wheel packages

Size Wheel Diameter Difference Sidewall
265/70R17 17 in 31.61 in +0.03 in 7.30 in
265/65R18 18 in 31.56 in 0.01 in 6.78 in
245/60R20 20 in 31.57 in — 5.79 in

A truck offered with all three is offered one rolling diameter. The speedometer, the odometer, the axle ratio and the transfer case see no difference at all. What changes is the sidewall — 7.30 in on the 17 against 5.79 in on the 20 — and 0.79 in of section width.

That is the point of the exercise. A manufacturer cannot recalibrate the drivetrain per wheel option, so the tire absorbs the wheel change entirely.

Around 31.5 inches

265/75R16 is 0.07 in taller at 31.65 in, on a wheel four inches smaller with 7.82 in of sidewall. 245/75R17 is 0.11 in shorter at 31.47 in on the same 9.65 in of section. 235/85R16 is 0.15 in taller at 31.73 in and narrower still.

Six codes, four wheel diameters, a quarter of an inch of spread. On a full-size truck this is the band that the drivetrain was designed around, and almost everything the market offers for one lands inside it.

Sidewall and load

5.79 in on a 20-inch wheel is a working amount of casing rather than a styling one, and the load index in this size runs high because the vehicles carry weight. The number printed after the code is the one to read against the door-jamb placard; the load index table converts it.

At 638.7 revolutions per mile this size sits firmly in the light-truck band, and that figure is the quantity every gearing calculation starts from. A truck moving between the three wheel packages above keeps the same figure to within a few tenths, which is precisely why the manufacturer can offer all three without changing the axle.

Related

Class: Crossover and SUV. Every figure above is computed from the size code, not stored — see how these numbers are calculated.