255/55R20 in inches

A 255/55R20 tire is 31.0″ tall and 10.0″ wide, and fits a 20″ wheel. In inches it is written 31.0×10.0R20.

Diameter31.04″

Width10.04″

Sidewall5.52″

Drawn to scale. Nominal dimensions calculated from the size code.

Manufacturer data

How tall 255/55R20 tires really are

Heights published by BFGoodrich, General, Michelin and Toyo for all 19 tires in this size. Their published revolutions per mile work out to 30.1″ under load (below).

Real 255/55R20 tires measure 31.00–31.02″, against 31.04″ from the size code. Most run shorter than the size code (18 of 19).

Height under load30.1″

Published revs per mile (669–671) mean the tire rolls like a 30.1″ tire on the vehicle. Use this for speedometer calibration.

Weight spread31.3–44.1 lb

The lightest (Michelin Pilot Sport All-Season 4, XL) is 12.8 lb lighter per corner than the heaviest (BFGoodrich Trail-Terrain T/A+, XL).

19 tires in 255/55R20

Sort by the spec you care about.

	Load					Revs/mi	Source
Michelin Pilot Sport All-Season 4Performance	XL · 110Y	31.00	31.3	10.0	2,337	671	Spec page
Michelin CrossClimate2All-season	XL · 110V	31.00	32.4	10.0	2,337	671	Spec page
Michelin Pilot Sport 4 SUVPerformance	XL · 110Y	31.00	32.4	9.5	2,337	671	Spec page
Michelin Pilot Sport All-Season 4Performance	XL · 110V	31.00	33.3	9.0	2,337	671	Spec page
Michelin Pilot Sport EVPerformance	XL · 110Y	31.00	33.3	8.5	2,337	671	Spec page
Michelin Pilot Alpin 5Winter	XL · 110V	31.02	34.0	10.5	2,337	671	Spec page
Michelin Defender2All-season	XL · 110H	31.00	34.3	10.5	2,337	671	Spec page
Michelin Primacy All SeasonTouring	XL · 110V	31.00	34.6	9.5	2,337	671	Spec page
General Grabber H/THighway	SL · 107H	31.00	35.0	12.0	2,149	669	Spec page
Michelin X-Ice SnowWinter	XL · 110T	31.02	35.6	10.5	2,337	671	Spec page
BFGoodrich Advantage ControlAll-season	XL · 110H	31.02	35.9	11.5	2,337	671	Spec page
Toyo Open Country A/T IIIAll-terrain	XL · 110H	31.02	37.3	13.2	2,337	670	Spec page
Toyo Observe G3-IceWinter	XL · 110T	31.02	37.7	12.0	2,337	670	Spec page
Toyo Proxes G-Tour	XL · 110V	31.02	38.1	12.1	2,337	670	Spec page
Toyo OPEN COUNTRY Q/TAll-season	XL · 110V	31.02	39.1	12.2	2,337	670	Spec page
Toyo Open Country H/T IIHighway	XL · 110H	31.02	42.4	11.0	2,337	670	Spec page
BFGoodrich Trail-Terrain T/AAll-terrain	XL · 110H	31.00	42.9	12.5	2,337	671	Spec page
BFGoodrich Trail-Terrain T/A+	XL · 110H	31.00	44.1	12.5	2,337	671	Spec page
General Grabber Arctic XWinter	XL · 110T	31.00	–	12.0	2,337	669	Spec page

Is 255/55R20 a 31-inch tire?

≈31″

Yes. The size code works out to 31.04″, and the 19 tires here publish 31.00–31.02″, so people call it a 31.

All 31-inch tire sizes, on every wheel size.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

Size	Diameter ″	vs 255/55R20	Difference
265/50R20	30.43	-0.61″	-2.0%
295/45R20	30.45	-0.59″	-1.9%
305/45R20	30.81	-0.24″	-0.8%
275/50R20	30.83	-0.22″	-0.7%
255/50R21	31.04	-0.00″	-0.0%
255/60R19	31.05	+0.00″	+0.0%
235/60R20	31.10	+0.06″	+0.2%
285/50R20	31.22	+0.18″	+0.6%
265/55R20	31.48	+0.43″	+1.4%
245/60R20	31.57	+0.53″	+1.7%

How to read 255/55R20

How to read any tire size

How 255/55R20 110H is printed on the sidewall. It's the most common code among the 19 tires here (6 of them); tires in this size come in other load and speed ratings too.

1255Section width

255 mm across the widest point, or 10.04 inches. Every 255 size

255Aspect ratio

A percentage, not a measurement: the sidewall is 55% as tall as the tire is wide, which is 140.3 mm or 5.52 inches.

3RConstruction

Radial construction.

420Wheel diameter

Mounts on a 20-inch wheel. Approved wheel widths run 7.0″ to 9.0″.

5110Load index

Each tire carries up to 2,337 lb (1,060 kg) at its maximum pressure.

6HSpeed rating

Rated for up to 130 mph sustained.

XLExtra load

Printed after the size. In this size the XL tires carry up to 2,337 lb each and the standard-load tires up to 2,149 lb, as published.

Specification	Inches	Metric
Overall diameter	31.04	789 mm
Section width	10.04	255 mm
Sidewall height	5.52	140.3 mm
Circumference	97.5	2,477 mm
Revolutions per mile (calculated, unloaded)	649.7	404 per km
Revolutions per mile (published by manufacturers)	669–671	416–417 per km
Approved wheel width	7.0–9.0	178–229 mm

Speedometer error after switching to 255/55R20

Your actual speed– mph

Questions about 255/55R20

What is 255/55R20 in inches?

31.04 inches tall, 10.04 inches wide, on a 20-inch wheel. Written in inches, that is roughly 31.0×10.0R20.

How much does a 255/55R20 tire weigh?

Between 31.3 lb and 44.1 lb for the 18 tires listed here. The lightest is the Michelin Pilot Sport All-Season 4 (XL); the heaviest is the BFGoodrich Trail-Terrain T/A+ (XL).

What wheel width do I need for 255/55R20?

Manufacturers approve 7.0–9.0″ wide wheels for this size.

How many revolutions per mile does a 255/55R20 make?

Published figures run 669–671 revolutions per mile. The calculated figure is 649.7, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 255/55R20 than 275/50R20?

0.22 inches taller on paper (31.04″ vs 30.83″), which raises the axle about 0.11″. Your speedometer will read about 0.7% slow.