How tall is a 275/55R20 tire?

31.91 inches (810.5 mm) nominal. A new tire may measure from 31.55 to 32.39 in under the official tolerance; the maker's specification gives the figure for a specific tire.

How wide is a 275/55R20 tire?

10.83 inches (275.0 mm) section width. Overall width can be slightly larger; for passenger tires, US rule FMVSS 139 allows 7% over the specified width (or 10 mm, if larger, for some pressure classes).

How many revolutions per mile does 275/55R20 make?

About 632 nominal, from a circumference of 100.25 in. Tire makers publish measured revolutions per mile for each tire.

Will 275/55R20 fit my vehicle?

This page can't tell you. Check the tire size on your door-jamb placard , then confirm wheel width, offset and clearance with the tire or vehicle maker.

275/55R20 tire size in inches

A 275/55R20 tire is 31.91 inches tall and 10.83 inches wide on a 20-inch rim. These are nominal dimensions from the official sizing formula.

Tire size information275/55R20

Dimension	275/55R20		This size vs yours
Overall diameter UN R30 §6.1.2.1	31.91 in 810.5 mm
Section width UN R30 §6.1.2.1	10.83 in 275.0 mm
Sidewall height UN R30 §6.1.2.1	5.95 in 151.3 mm
Rim diameter Marked on the tire	20 in
Circumference From diameter	100.25 in
Revolutions per mile From diameter	632
Allowed real diameter UN R30 §6.1.5	31.55–32.39 in

Nominal, not measuredReal tires vary by brand and load range.

Drawn to scale on one ground line, with the next size down and up on the same rim. The dashed line marks the height of 275/55R20.

Is 275/55R20 a 32-inch tire?

Yes. At 31.91 inches tall, 275/55R20 is commonly called a 32-inch tire. Inch-class names round to the nearest inch; the true nominal height is 31.91 in, and a new tire may legally measure between 31.55 and 32.39 in.

See all 32-inch tire sizes.

Speedometer change

Your speedometer shows mphTrue speed 59.2 mph (−0.8 mph)

Example: if your speedometer is calibrated for 285/55R20 and you fit 275/55R20, the tire is −1.3% in diameter, so your true speed differs from the reading as shown below. Enter your current size above to see your own figures.

Speedometer reading versus true speed
Reading	True speed	Difference
30 mph	29.6 mph	−0.4 mph
45 mph	44.4 mph	−0.6 mph
55 mph	54.3 mph	−0.7 mph
60 mph	59.2 mph	−0.8 mph
70 mph	69.1 mph	−0.9 mph
80 mph	78.9 mph	−1.1 mph

Sizes within 3% of 275/55R20

These sizes are within 3% of the diameter of 275/55R20. The 3% figure is a rule of thumb, not a regulation and not a fitment check: wheel width, offset, suspension and body clearance decide what fits. See changing tire size.

Sizes within 3% of 275/55R20
Size	Diameter (in)	Width (in)	Change	Ride height (in)
255/70R17	31.06	10.04	−2.7%	−0.43
245/75R17	31.47	9.65	−1.4%	−0.22
265/65R18	31.56	10.43	−1.1%	−0.17
265/70R17	31.61	10.43	−1.0%	−0.15
265/75R16	31.65	10.43	−0.8%	−0.13
235/85R16	31.73	9.25	−0.6%	−0.09
275/55R20	31.91	10.83	—	—
255/75R17	32.06	10.04	+0.5%	+0.07
275/65R18	32.07	10.83	+0.5%	+0.08
275/70R17	32.16	10.83	+0.8%	+0.12
285/55R20	32.34	11.22	+1.4%	+0.22
265/60R20	32.52	10.43	+1.9%	+0.31
33x12.50R15	32.52	12.52	+1.9%	+0.31
285/65R18	32.59	11.22	+2.1%	+0.34
265/70R18	32.61	10.43	+2.2%	+0.35
285/70R17	32.71	11.22	+2.5%	+0.40
295/55R20	32.78	11.61	+2.7%	+0.43
305/70R16	32.81	12.01	+2.8%	+0.45
285/75R16	32.83	11.22	+2.9%	+0.46

Inch equivalent of 275/55R20

In inch terms, 275/55R20 is about 31.9x10.8R20: 31.9 in tall and 10.8 in wide, a 32-inch tire.

Nearest inch (flotation) sizes, same rim first. Diameter change is from 275/55R20.
Inch size	Diameter (in)	Change	Width (in)	Dimensions from
33x12.50R20	33.00	+3.4%	12.50	numbers in the size
32x11.50R15	31.54	−1.2%	11.42	UN R54 table
33x12.50R15	32.52	+1.9%	12.52	UN R54 table

How 275/55R20 is calculated

275 mm section width × 55% aspect ratio = 151.3 mm sidewall (5.95 in).

Overall diameter = rim + 2 × sidewall = 20 in + 2 × 5.95 in = 31.91 in.

Formula: UN Regulation No. 30 §2.15 and §6.1.2.1 (passenger) and UN Regulation No. 54 §6.1.2.1 (light truck). Revolutions per mile = 63,360 ÷ circumference. Full sources are listed at the end of this page.

Questions about 275/55R20

How tall is a 275/55R20 tire?: 31.91 inches (810.5 mm) nominal. A new tire may measure from 31.55 to 32.39 in under the official tolerance; the maker's specification gives the figure for a specific tire.
How wide is a 275/55R20 tire?: 10.83 inches (275.0 mm) section width. Overall width can be slightly larger; for passenger tires, US rule FMVSS 139 allows 7% over the specified width (or 10 mm, if larger, for some pressure classes).
How many revolutions per mile does 275/55R20 make?: About 632 nominal, from a circumference of 100.25 in. Tire makers publish measured revolutions per mile for each tire.
Will 275/55R20 fit my vehicle?: This page can't tell you. Check the tire size on your door-jamb placard, then confirm wheel width, offset and clearance with the tire or vehicle maker.

Printed from https://tiresizecalc.net/size/275-55r20/. Figures as published on 2026-11-01. The full working and the official sources are on that page.

Sources

This size is listed by the manufacturer: Goodyear Wrangler Steadfast HT, checked on the manufacturer's site on 2026-11-01. The size page shows nominal figures, not that product's measurements.

UN Regulation No. 30 - Uniform provisions concerning the approval of pneumatic tyres for motor vehicles and their trailers (Revision 3). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.29/Rev.3. 2007-03-29. Para 2.15 and 6.1.2.1: aspect ratio and outer diameter, D = d + 2H. Retrieved 2026-11-01.
UN Regulation No. 54 - Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers (Revision 2). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.53/Rev.2. 2004-04-16. Para 6.1.2.1: the same formula for light truck tires. Retrieved 2026-11-01.
UN Regulation No. 30 - Uniform provisions concerning the approval of pneumatic tyres for motor vehicles and their trailers (Revision 3). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.29/Rev.3. 2007-03-29. Para 6.1.5: allowed outer diameter, Dmin = d + 2H x 0.97, Dmax = d + 2H x 1.04. Retrieved 2026-11-01.
UN Regulation No. 54 - Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers (Revision 2). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.53/Rev.2. 2004-04-16. Annex 5 Part II Table B: design outer diameter and section width of 33x12.50R15LT. Retrieved 2026-11-01.
UN Regulation No. 54 - Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers (Revision 2). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.53/Rev.2. 2004-04-16. Para 6.1.5.1, 6.1.5.3.1 and Table B note 2: allowed outer diameter for table sizes. Retrieved 2026-11-01.
Computed by tiresizecalc.net from the cited formula. Sri Murugan Systems. Circumference = pi x diameter; revolutions per mile = 63,360 / circumference; 1 in = 25.4 mm exactly. Retrieved 2026-11-01.
49 CFR 571.139 - Standard No. 139; New pneumatic radial tires for light vehicles. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations (eCFR). 49 CFR 571.139. eCFR up to date as of 2026-10-15. S6.1.2: passenger tire width up to 7 percent (or 10 mm) over the specified width. Retrieved 2026-11-01.
49 CFR 571.110 - Standard No. 110; Tire selection and rims for motor vehicles with a GVWR of 4,536 kilograms (10,000 pounds) or less. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations, annual edition (GovInfo). 2006-10-01. S4.3: the door placard shows the original tire size. Retrieved 2026-11-01.

Last reviewed 2026-11-01. The full source list, with dates and file checksums, is in How the numbers are calculated. To report an error, email contactus@tiresizecalc.net.