tireheight.com

255/55R18 in inches

A 255/55R18 tire is 29.0″ tall and 10.0″ wide, and fits a 18″ wheel. In inches it is written 29.0×10.0R18.

Diameter29.04″
Width10.04″
Sidewall5.52″
255/55R18 drawn to scale: 29.04 inch diameter, 5.52 inch sidewall, 18 inch wheel, 10.04 inch tread width18″ wheel5.52″29.04″ overall10.04″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 255/55R18 tires really are

Heights published by BFGoodrich, General, Michelin and Toyo for all 23 tires in this size. Their published revolutions per mile work out to 28.1–28.2″ under load (below).

Real 255/55R18 tires measure 29.00–29.02″, against 29.04″ from the size code. Every one runs shorter than the size code.

Height under load28.1–28.2″

Published revs per mile (715–717) mean the tire rolls like a 28.1–28.2″ tire on the vehicle. Use this for speedometer calibration.

Weight spread29.5–48.1 lb

The lightest (General AltiMAX365 AW, XL) is 18.6 lb lighter per corner than the heaviest (BFGoodrich All-Terrain T/A KO3, LT D).

23 tires in 255/55R18

Sort by the spec you care about.

LoadRevs/miSource
General AltiMAX365 AWTouringXL · 109V29.0029.511.02,271715Spec page
Michelin Latitude Sport 3PerformanceSL · 105W29.0029.88.52,039717Spec page
Michelin Latitude Tour HPAll-seasonSL · 105V29.0030.29.51,854717Spec page
Michelin Latitude Sport 3PerformanceSL · 105W29.0030.48.52,039717Spec page
Michelin Pilot Sport 4 SUVPerformanceXL · 109Y29.0030.89.52,271717Spec page
Michelin Defender LTX M/SAll-seasonXL · 109H29.0031.110.52,271717Spec page
BFGoodrich Advantage ControlAll-seasonXL · 109V29.0231.810.52,271717Spec page
Michelin Latitude AlpinWinterXL · 109V29.0032.610.52,271717Spec page
Michelin Latitude SportPerformanceXL · 109Y29.0032.710.02,064717Spec page
Michelin X-Ice SnowWinterXL · 109T29.0232.710.52,271717Spec page
Michelin Latitude Alpin LA2WinterXL · 109V29.0232.910.02,271717Spec page
Toyo Proxes ST IIIPerformanceXL · 109V29.0233.010.12,271716Spec page
Toyo Observe G3-IceWinterXL · 109T29.0234.212.02,271716Spec page
Michelin Latitude Tour HPAll-seasonXL · 109V29.0034.49.52,064717Spec page
General Grabber HTS60TouringXL · 109H29.0034.712.02,271715Spec page
Toyo Celsius IITouringXL · 109V29.0234.711.52,271716Spec page
Toyo OPEN COUNTRY Q/TAll-seasonXL · 109V29.0235.512.22,271716Spec page
Toyo Open Country A/T IIIAll-terrainXL · 109H29.0236.213.22,271716Spec page
BFGoodrich Trail-Terrain T/AAll-terrainXL · 109H29.0038.812.52,271717Spec page
BFGoodrich Trail-Terrain T/A+XL · 109H29.0040.012.52,271717Spec page
Michelin Latitude Sport 3PerformanceXL · 109V29.0040.58.52,271717Spec page
Michelin Latitude Alpin LA2WinterXL · 109H29.0240.810.02,271717Spec page
BFGoodrich All-Terrain T/A KO3All-terrainLT D · 109S29.0048.115.02,270717Spec page

Is 255/55R18 a 29-inch tire?

≈29″

Yes. The size code works out to 29.04″, and the 23 tires here publish 29.00–29.02″, so people call it a 29.

All 29-inch tire sizes, on every wheel size.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 255/55R18Difference
235/55R1828.18-0.87″-3.0%
295/45R1828.45-0.59″-2.0%
245/55R1828.61-0.43″-1.5%
225/60R1828.63-0.41″-1.4%
235/65R1729.03-0.02″-0.1%
255/50R1929.04-0.00″-0.0%
255/60R1729.05+0.00″+0.0%
285/45R1929.10+0.06″+0.2%
235/60R1829.10+0.06″+0.2%
245/60R1829.57+0.53″+1.8%

How to read 255/55R18

How to read any tire size

255/55R18 109V as printed on the tire sidewall, with each part numbered255/55R18 109V123456
How 255/55R18 109V is printed on the sidewall. It's the most common code among the 23 tires here (9 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.

418Wheel diameter

Mounts on a 18-inch wheel. Approved wheel widths run 7.0″ to 9.0″.

5109Load index

Each tire carries up to 2,271 lb (1,030 kg) at its maximum pressure.

6VSpeed rating

Rated for up to 149 mph sustained.

XLExtra load

Printed after the size. In this size the XL tires carry up to 2,271 lb each and the standard-load tires up to 2,039 lb, as published.

SpecificationInchesMetric
Overall diameter29.04738 mm
Section width10.04255 mm
Sidewall height5.52140.3 mm
Circumference91.22,318 mm
Revolutions per mile (calculated, unloaded)694.4431 per km
Revolutions per mile (published by manufacturers)715–717444–446 per km
Approved wheel width7.0–9.0178–229 mm

Speedometer error after switching to 255/55R18

Your actual speed– mph

Questions about 255/55R18

What is 255/55R18 in inches?

29.04 inches tall, 10.04 inches wide, on a 18-inch wheel. Written in inches, that is roughly 29.0×10.0R18.

How much does a 255/55R18 tire weigh?

Between 29.5 lb and 48.1 lb for the 23 tires listed here. The lightest is the General AltiMAX365 AW (XL); the heaviest is the BFGoodrich All-Terrain T/A KO3 (LT D).

What wheel width do I need for 255/55R18?

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

How many revolutions per mile does a 255/55R18 make?

Published figures run 715–717 revolutions per mile. The calculated figure is 694.4, but manufacturers measure the tire under load, where it rolls on a smaller radius.

What is the difference between P255/55R18 and LT255/55R18?

Passenger tires (22 here) are built for passenger loads, with max loads of 1854–2271 lb. Light-truck tires (1 here) come in heavier load ranges with max loads of 2270 lb, and are usually heavier with deeper tread.

How much taller is 255/55R18 than 225/60R18?

0.41 inches taller on paper (29.04″ vs 28.63″), which raises the axle about 0.21″. Your speedometer will read about 1.4% slow.