Data sheet TS-285/55R20 · Size

285/55R20 in inches

By the formula 285/55R20 measures 32.3 in overall diameter and 11.2 in section width (822 mm and 285 mm). See maker tables and measured models below.

Fig. 1 — Cross-section

A section width, B sidewall, C rim, D overall diameter. Nominal, on the measuring rim.

Table 1 — Nominal dimensions

285/55R20: nominal dimensions in inches and millimeters
Item	in	mm
Overall diameter	32.34	822
Section width	11.22	285
Sidewall	6.17	156.8
Rim	20	508.0
Circumference	101.6	2,581
Revs per mile · km	624	387

From the makers’ size tables
Flotation size printed	33X11.50R20LT	Mickey Thompson
Measuring rim	9″	Nitto LT
Approved rims	8.5–10.0, 8.0–10.0″	13 LT tires

Table 2 — Measured range

32.36–32.70″overall diameter, 17 tires from 5 makers (math: 32.34″)

53–67 lbweight, 13 LT versions

13.6–19.0/32″new tread depth

3,305 lbmax load per tire, 12 of 13 LT versions list it, as published

13 LT · 4 Pversions in the makers’ tables we read

All 17 tires ↓

Table 3

17 tires in 285/55R20, as published

One row per model and type, from each maker’s size table. LT first, then P-metric; sorted by diameter.

The math says 32.34″. 17 tires from 5 makers measure 32.36″–32.70″. Tallest here: Mickey Thompson Baja Boss A/T (all-terrain), 32.70″. Check the maker’s number before you buy for a tight fit.

Published dimensions for 285/55R20
Tire	Type	Diameter	Width	Rims, in	Weight	Tread	Max load
Nitto Recon Grappler A/Tnittotire.com · Oct 15, 2026	LT · E 122/119S	32.36″	11.69″	8.5–10.0	56.7 lb	16.0/32″	3,305 lb @ 80 psi
Nitto Terra Grappler G3nittotire.com · Oct 15, 2026	LT · E 122/119T	32.36″	11.69″	8.5–10.0	54.5 lb	16.0/32″	3,305 lb @ 80 psi
Firestone Destination X/Tfirestonetire.com · Oct 15, 2026	LT · E 122R	32.40″	—	8.0–10.0	52.5 lb	16.0/32″	—
Kumho Road Venture AT52kumhotireusa.com · Oct 15, 2026	LT · E 122/119R	32.40″	11.70″	8.5–10.0	56.2 lb	16.0/32″	3,305 lb @ 80 psi
Kumho Road Venture RTkumhotireusa.com · Oct 15, 2026	LT · E 122/119R	32.40″	11.70″	8.5–10.0	61.6 lb	17.3/32″	3,305 lb @ 80 psi
Toyo Open Country A/T IIItoyotires.com · Oct 15, 2026	LT · E 122/119T	32.40″	11.70″	8.5–10.0	54.0 lb	16.5/32″	3,305 lb @ 80 psi
Toyo Open Country R/T Trailtoyotires.com · Oct 15, 2026	LT · E 122/119Q	32.40″	11.70″	8.5–10.0	58.0 lb	16.5/32″	3,305 lb @ 80 psi
Kumho Road Venture MT71kumhotireusa.com · Oct 15, 2026	LT · E 122/119Q	32.60″	11.70″	8.5–10.0	66.6 lb	19.0/32″	3,305 lb @ 80 psi
Mickey Thompson Baja Legend EXPmickeythompsontires.com · Oct 15, 2026	LT · E 122Q	32.60″	11.70″	8.0–10.0	59.0 lb	18.5/32″	3,305 lb @ 80 psi
Mickey Thompson Baja Boss M/Tmickeythompsontires.com · Oct 15, 2026	LT · E 122Q	32.60″	11.70″	8.0–10.0	63.0 lb	18.5/32″	3,305 lb @ 80 psi
Nitto Ridge Grapplernittotire.com · Oct 15, 2026	LT · E 122/119Q	32.60″	11.69″	8.5–10.0	61.1 lb	16.4/32″	3,305 lb @ 80 psi
Nitto Trail Grappler M/Tnittotire.com · Oct 15, 2026	LT · E 122/119Q	32.60″	11.69″	8.5–10.0	63.2 lb	18.9/32″	3,305 lb @ 80 psi
Mickey Thompson Baja Boss A/Tmickeythompsontires.com · Oct 15, 2026	LT · E 122Q	32.70″	11.50″	8.0–10.0	62.0 lb	18.5/32″	3,305 lb @ 80 psi
Nitto Recon Grappler A/Tnittotire.com · Oct 15, 2026	XL 116T	32.36″	11.69″	8.0–10.0	47.0 lb	13.6/32″	2,756 lb @ 50 psi
Nitto Terra Grappler G3nittotire.com · Oct 15, 2026	XL 116T	32.36″	11.69″	8.0–10.0	46.8 lb	13.6/32″	2,756 lb @ 50 psi
Toyo Open Country A/T IIItoyotires.com · Oct 15, 2026	SL 114T	32.40″	11.70″	8.0–10.0	45.0 lb	13.6/32″	2,601 lb @ 44 psi
Toyo Open Country R/T Trailtoyotires.com · Oct 15, 2026	XL 116T	32.40″	11.70″	8.0–10.0	46.0 lb	13.6/32″	2,756 lb @ 50 psi

§ 1

Nominal numbers by the formula

285/55R20 by the formula has an overall diameter of 32.3 in (822 mm), a section width of 11.2 in (285 mm) and a sidewall height of 6.2 in (157 mm). The rim is 20 in (508 mm).

Circumference calculates to 101.6 in (2,581 mm). Revolutions per mile are 624 (387 per km). These are unloaded nominal numbers by the formula; real tires measure slightly differently.

§ 2

What makers publish and measure

Makers' public size tables list 17 tires in 285/55R20 from five brands checked October 15, 2026. Thirteen are LT and four are P-metric; listed load ranges include SL, XL and E.

Published overall diameters run from 32.36 in to 32.7 in, compared with 32.3 in by the formula. Reported weights run from 45 lbs to 66.6 lbs and new tread depths from 13.6/32 in to 19/32 in. Examples: Nitto Recon Grappler A/T, LT285/55R20, overall diameter 32.36 in, overall width inflated 11.69 in, weight 56.7 lbs, tread depth 16/32 in (Nitto). Toyo Open Country A/T III, LT285/55R20, overall diameter 32.4 in, weight 54 lbs, tread depth 16.5/32 in and 642 revs per mile (Toyo). Mickey Thompson Baja Legend EXP, LT285/55R20, overall diameter 32.6 in, section width 11.7 in, weight 59 lbs; maker lists equivalent 33X11.50R20LT (Mickey Thompson).

§ 3

Closest sizes within ±3%

The neighbor window on this page uses a ±3% overall-diameter rule of thumb used by tire shops; it is not a law. Sizes within 3% of 285/55R20 include 265/60R20, 305/50R20, 275/55R20, 295/55R20 and others; see the comparison tool for the full list.

Examples of what changes: moving to 265/60R20 increases diameter by 0.5% (+0.18 in, +5 mm). At an indicated 60 mph true speed becomes 60.3 mph; revolutions per mile change 624 → 620; axle ground clearance +0.09 in (+2 mm). Moving to 305/50R20 reduces diameter by 1.0% (−0.33 in, −9 mm); at an indicated 60 mph true speed becomes 59.4 mph; revolutions per mile change 624 → 630; axle clearance −0.17 in (−4 mm).

265/60R20 (32.5 in, +0.5%) — see /tire-sizes/265-60r20/
305/50R20 (32.0 in, −1.0%) — see /tire-size-comparison/
275/55R20 (31.9 in, −1.3%) — see /tire-sizes/275-55r20/

Fig. 2

285/55R20 and the sizes next to it

To scale, on one ground line. Diameter by the formula.

Table 4

Compare 285/55R20 with another size

Type any size: diameter, sidewall, speedometer and clearance change against this one.

Comparison

275/60R20 is 32.99″ tall, +2.01% against 285/55R20. At 60 mph on the dial you drive 61.2 mph.

285/55R20 vs 275/60R20
Item	285/55R20	275/60R20	Change
Overall diameter	32.34″	32.99″	+0.65″ +2.01%
Section width	11.22″	10.83″	−0.39″
Sidewall	6.17″	6.50″	+0.32″
Circumference	101.6″	103.6″	+2.0″
Revs per mile	624	611	−12
Axle height	16.17″	16.50″	+0.32″

When the odometer counts 1,000 miles, you have driven 1,020.1 miles.

Engine RPM at the same road speed: −2.0%. Gear ratio calculator

Speedometer

Speedometer reading and true speed
Dial shows	True speed	Difference
30 mph	30.6 mph	+0.6
45 mph	45.9 mph	+0.9
60 mph	61.2 mph	+1.2
70 mph	71.4 mph	+1.4
80 mph	81.6 mph	+1.6

285/55R20275/60R20

Note 1

P-metric or LT in the same size

Nitto Recon Grappler A/T is published in both versions.

Nitto Recon Grappler A/T, 285/55R20: P and LT
Nitto Recon Grappler A/T	P · 116T	LT · E · 122/119S
Overall diameter	32.36″	32.36″
Max load	2,756 lb @ 50 psi	3,305 lb @ 80 psi
Weight	47.0 lb	56.7 lb
Tread depth	13.6/32″	16.0/32″
Approved rims	8.0–10.0″	8.5–10.0″

Source: Nitto size table, checked Oct 15, 2026. On trucks and SUVs, the load ratings of the tires on an axle must add up to at least the axle’s GAWR on the certification label (49 CFR 571.110).

Vehicles on 285/55R20: not listed yet. We add a vehicle here only from its maker’s own spec sheet for that year and trim.

The size your vehicle left the factory on is printed on the tire and loading placard on the driver’s door jamb (49 CFR 571.110). Pressure and load: that placard too.

Table 5

Within 3% of 285/55R20

Same rim or ±1″, diameter within 3%. A shop rule of thumb, not a law.

Sizes within 3% of 285/55R20
Size	Diameter	Width	vs 285/55R20	At 60 mph	Clearance
265/60R20	32.52″	10.4″	+0.5%	60.3	+0.09″
305/50R20	32.01″	12.0″	−1.0%	59.4	−0.17″
275/55R20	31.91″	10.8″	−1.3%	59.2	−0.22″
295/55R20	32.78″	11.6″	+1.3%	60.8	+0.22″
275/50R21	31.83″	10.8″	−1.6%	59.0	−0.26″
275/60R20	32.99″	10.8″	+2.0%	61.2	+0.32″
33x11.50R20	33.00″	11.5″	+2.0%	61.2	+0.33″
33x12.50R20	33.00″	12.5″	+2.0%	61.2	+0.33″
245/60R20	31.57″	9.6″	−2.4%	58.6	−0.38″
305/55R20	33.21″	12.0″	+2.7%	61.6	+0.43″

Other 20″ sizes

Q&A

Common questions

How many revolutions per mile does 285/55R20 make?

By the formula 285/55R20 makes 624 revolutions per mile (387 per km).

What load ranges and tire versions are available in 285/55R20?

Makers list 17 tires from five brands: 13 LT and 4 P-metric. Published load ranges include SL, XL and E; LT tires show the load range letter on the sidewall as required by 49 CFR 571.139 (FMVSS No. 139).

Where do I find the vehicle inflation pressure and load limits?

See the tire and loading placard on the driver's side B-pillar (door jamb) for the vehicle maker's recommended cold tire inflation pressure and load information (49 CFR 571.110).

How do maker measurements compare with the formula?

Published overall diameters run about 32.36 in to 32.7 in, which is slightly above the formula nominal value listed for 285/55R20 (checked October 15, 2026).

Notes

Method and sources

Each number and rule comes from a source with the date it was checked.

Sidewall = width × aspect ratio ÷ 100
Diameter = rim × 25.4 + 2 × sidewall (mm)
Revs per mile = 63,360 ÷ (π × diameter, in)
True speed = dial × new diameter ÷ old diameter
Clearance change = half the diameter change

Numbers are nominal: the tire unloaded, on its measuring rim. Revs per mile published by makers run higher than the formula. “Within 3%” is a rule of thumb tire shops use, not a law. Tire pressure: the placard on your door jamb.

Nitto: size table (nittotire.com)checked Oct 15, 2026
Toyo: size table (toyotires.com)checked Oct 15, 2026
Mickey Thompson: size table (mickeythompsontires.com)checked Oct 15, 2026
49 CFR 571.139 (FMVSS No. 139), S5.5(d)ecfr.gov · checked Oct 15, 2026
49 CFR 571.110 (FMVSS No. 110), S4.3ecfr.gov · checked Oct 15, 2026

Calculators and size classes

33″22 metric and 11 flotation sizes measure 32.5–33.5″ by the formula305/70R16 · 285/75R16 · 295/75R16 · 305/65R17 · 285/70R17 35″15 metric and 16 flotation sizes measure 34.5–35.5″ by the formula315/75R16 · 325/65R18 · 305/70R18 · 285/75R18 · 285/65R20 37″3 metric and 13 flotation sizes measure 36.5–37.5″ by the formula385/70R16 · 315/80R17 · 375/45R24