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Tire size · 20-inch wheel · about 31.0x10.0R20

255/55R20 tire size

Overall diameter, nominal31.0 in

Estimate ±789 mm

A 255/55R20 tire is 31.0 in (789 mm) tall and 10.0 in (255 mm) wide on a 20-inch wheel, with a 5.5 in sidewall, and turns about 650 times a mile.

Stock on the Chevrolet Colorado (2025–2026, with a package) and Ford Explorer (2020 and 2025), per their makers’ documents.

Width
10.0 in
Sidewall
5.5 in
Wheel
20 in
Revs per mile
650

01 / Dimensions

255/55R20 in inches and millimeters

What the size code works out to. A real tire of the size measures within about 1.5% of it, by brand, tread, wheel width and pressure.

255/55R20

Estimate ±
Overall diameter
31.0 in 789 mm30.6 to 31.5 in for real tires
Section width
10.0 in 255 mm
Sidewall height
5.5 in 140 mm
Wheel diameter
20 in 508 mm
Circumference
97.5 in 2,477 mm
Revolutions per mile
650 404 per km640 to 660

02 / Stock on

Vehicles that leave the factory on 255/55R20

Which configurations run it in which model years, printed the way each maker prints the size, and how it compares with the vehicle’s other stock sizes. A speedometer set for one of those reads off by the amount shown when you fit 255/55R20 instead.

  • Chevrolet ColoradoMaker
    • 2025–2026 · Z71 with the Z71 with P255/55R20 all-season tiresprinted P255/55R20

    Chevrolet Colorado model years on 255/55R20:

    Its other stock sizes

    • 285/70R17 (2025–2026 · ZR2). 255/55R20 is 1.7 in shorter: with a speedometer set for 285/70R17 it reads 5.4% high, 56.9 mph at an indicated 60.
    • 265/65R18 (2025–2026 · Z71, Trail Boss). 255/55R20 is 0.5 in shorter: with a speedometer set for 265/65R18 it reads 1.7% high, 59.0 mph at an indicated 60.
    • 255/65R17 (2025–2026 · WT). 255/55R20 is 1.0 in taller: with a speedometer set for 255/65R17 it reads 3.2% low, 62.0 mph at an indicated 60.
  • Ford ExplorerMaker
    • 2025 · ST-Line; Platinumprinted P255/55R20
    • 2020 · Limitedprinted P255/55R20

    Ford Explorer model years on 255/55R20:

    Its other stock sizes

    • 255/65R18 (2025 · Active). 255/55R20 is the same height as 255/65R18, so a speedometer set for it reads true.
    • 275/45R21 (2025 · ST). 255/55R20 is 0.3 in taller: with a speedometer set for 275/45R21 it reads 1.0% low, 60.6 mph at an indicated 60.

Documents last checked . How we read them and what the marks mean: how we source the numbers. A figure doesn’t match its document? Report a wrong number.

03 / Nearby sizes

Sizes either side of 255/55R20

The nearest common upsizes and the next sizes down on the same wheel, from the stock sizes we cover and the sizes owners usually step up to, and sizes about as tall on another wheel.

Nearest sizes up

Nearest sizes up, compared with 255/55R20
SizeTallinHeightvs 255/55R20Widthvs 255/55R20At an indicated 60true mphCompare
265/55R2031.5+0.4 in+0.4 in60.859.9 to 61.7Compare →
245/60R2031.6+0.5 in−0.4 in61.060.1 to 61.9Compare →
275/55R2031.9+0.9 in+0.8 in61.760.7 to 62.6Compare →

Next sizes down

Next sizes down, compared with 255/55R20
SizeTallinHeightvs 255/55R20Widthvs 255/55R20At an indicated 60true mphCompare
275/50R2030.8−0.2 in+0.8 in59.658.7 to 60.5Compare →
235/55R2030.2−0.9 in−0.8 in58.357.5 to 59.2Compare →

About as tall, other wheels

About as tall, other wheels, compared with 255/55R20
SizeTallinHeightvs 255/55R20Widthvs 255/55R20At an indicated 60true mphCompare
255/65R1831.1±0.0 in±0.0 in60.059.1 to 60.9Compare →
255/70R1731.1±0.0 in±0.0 in60.059.1 to 60.9Compare →
275/65R1731.1±0.0 in+0.8 in60.159.2 to 61.0Compare →
31x10.50R1531.0±0.0 in+0.5 in59.959.0 to 60.8Compare →

04 / Next

Compare it with your size

Tire size calculator255/55R20 against 265/55R20, or any two sizes: height, speedometer and gearing.Compare sizesTire sizes by vehicleEvery stock size on the trucks and SUVs we cover.Browse sizesChevrolet Colorado tiresStock tires and wheels by trim, and what bigger tires change on the Chevrolet Colorado.See the tiresFord Explorer tiresStock tires and wheels by trim, and what bigger tires change on the Ford Explorer.See the tires

05 / FAQ

Questions people ask

What is 255/55R20 in inches?

About 31.0x10.0R20: 31.0 in tall and 10.0 in wide on a 20-inch wheel.

Which vehicles come with 255/55R20 tires?

In our data: Chevrolet Colorado (2025–2026, with a package) and Ford Explorer (2020 and 2025).

How does 255/55R20 compare with the Chevrolet Colorado’s other stock sizes?

255/55R20 is 1.7 in shorter: with a speedometer set for 285/70R17 it reads 5.4% high, 56.9 mph at an indicated 60. 255/55R20 is 0.5 in shorter: with a speedometer set for 265/65R18 it reads 1.7% high, 59.0 mph at an indicated 60. 255/55R20 is 1.0 in taller: with a speedometer set for 255/65R17 it reads 3.2% low, 62.0 mph at an indicated 60.

What is the next size up from 255/55R20?

265/55R20: about 0.4 in taller and 0.4 in wider. On a speedometer set for 255/55R20 it reads 1.4% low (60.8 mph at an indicated 60).