7 Simple Steps on How to Read Motorcycle Tire Size

This post has affiliate links. At no cost to you, we earn a commision for puchases made through links in this post. Read more

The tires of your motorcycle determine how your ride is going to be. Be it a cruiser, an off-road or a common bike, none can work without tires. However, in case you need to replace your beloved bike’s tire, you need to know all the essential information to determine the correct tire size.

We have designed a complete guide to help you learn how to read motorcycle tire size so that you don’t end up buying the wrong ones for your motorcycle.

Anatomy of a Motorcycle Tire

Let’s first get a brief overview of the architecture of a tire. A tire is just not a rubber piece molded into shape to fit the motorcycle wheels. Rather, it is made up of several components that build its strong, flexible, and reliable structure.

1. Tread

This is the part that comes in direct contact with the road. Tire tread is solely responsible for the motorcycle’s grip on the road. The tires are manufactured with different types of treads that are distinguished based on their patterns.

Tires with a smooth tread work more efficiently on smooth roads and dry surfaces as they avoid any additional friction that could affect the speed and grip of the motorcycle on the road. However, tires with deep tread patterns work best as tires for cruiser bikes or off-road dirt bikes.

2. Bead

This is the edge of the tire that sticks up to the rim. The tire bead is made of steel wires that are heavily coated with rubber to allow suction and a strong-grip with the motorcycle wheel. It is designed to fit snugly on the wheel to avoid slip-rotation of the tires.

3. Sidewall

A sidewall is a bridge between the tire tread and bead. It is a small component in the tire but plays the most crucial role in the stability and strength of the tire on-road. It is responsible for providing handling and load transferability to the motorcycle tire.

If you are struggling to learn how to read motorcycle tire size, the sidewalls play an important role. All the information related to the tire’s height, profile, and aspect ratio are mentioned on the tire sidewalls.

4. Carcass

The body of the tire beneath the tread is known as the carcass. The carcass is manufactured in two types, radial, that has reinforcing steel belts, and bias-ply tires whose cords are built of fiber (polyester or aramid).

Understand Tire Sizing Codes

If you wish to buy the best motorcycle tires, you must know how to read motorcycle tire size to decide the most suitable tires for your beloved motorcycle. But first, you must understand how the tire size is coded and engraved on the tires so that you can interpret the correct size.

Tire Size Format

Metric

  • This is the most common motorcycle tire size format.
  • For example, let’s assume the tire code is 180/70R-16
  • The first three digits (180) of the code represent the tire width in millimeters.
  • The fourth-fifth digits (70) represent the aspect ratio percentage of the tire which is also the height of the tire sidewalls.
  • The remaining digits (16) depict the rim size that the tire is suitable for.
  • Extra letters (R or B) between these digits refer to the tire build type.
  • The tire size code in the metric system uses numbers, R or B, ‘-’, and ‘/’ only.

Alphanumeric

  • Let’s assume MU85B16 to be the tire code.
  • The first set of letters (MU) refer to the street tire size.
  • The second letter set (B) helps to identify the tire build type.
  • The last numeric digits (16) are used to determine the rim diameter the tire is suitable for.
  • The alphanumeric tire size system is based on the tire size conversion chart.

Numeric

  • This tire code system is generally found on the dirt bike, vintage, or sidecar tires.
  • For example, 5.00-16 is the tire code.
  • The first digit(5.00) stands for the tire width in inches.
  • The second digit (16) is to determine the rim size

What are R and B?

R is for Radial tires that are made of several radially structured layers of rubber atop steel wires. The layers of the steel belts are stacked above each other and are located only in the tire tread. The radial tires are suitable for hot regions as they dissipate the heat faster. They also have thin sidewalls that provide abundant flexibility and stability to the motorcycle.

Bias Ply tires are coded as B or ‘-’ on the tires. These tires are suitable for heavy-duty load motorcycles such as cruiser bikes and tour motorcycles. These tires are made of numerous layers of cords stacked together from bead-to-bead all across the tire. Each alternating layer is made of nylon, rayon, or polyester. They have a strong and hard-quality sidewall build that can bear heavy weights.

Tire Type

  • WW: White-wall tire
  • TT: Tube-type tire (needs an additional inner air tube)
  • TL: Tubeless Tire
  • M/C: tire only for motorcycles

These codes indicate the tire type and can be found on a majority of tires.

Speed Rating

The letters in the tire codes apart from R & B, are used to determine the speed rating of the tire. Here’s a table to help you with the speed rating indications included in the tire size codes.

 Letter Code Max Speed in Mph Max speed in Kph
J62100
K68110
L75120
M81130
N87140
P93150
Q99160
R106170
S112180
T118190
U124200
H130210
V220137220
V230143230
V (also  V240)149240
V250155250
V260161260
V (also  V270)168270
V280174280
V290180290
Y (also 300)186300
ZAbove 149Above 240

Rim Width

Motorcycle tires are manufactured all around the globe, but this doesn’t mean all the tires have the same size designations. We have assembled a few common reference rim sizes that go along with tire sizes.

*This table is not suitable for the tires with an aspect ratio of less than 80.

Rim WidthMetricAlphanumeric
1.60, 1.8570MG
1.60, 1.8580MH
1.85, 2.1590MJ
1.85, 2.1590ML
2.15, 2.50100MM
2.15, 2.50, 2.75110MN
2.15, 2.50, 2.75110MP
2.15, 2.50, 2.75120MR
2.15, 2.50, 2.75120MS
2.50, 2.75, 3.00130MT
2.50, 2.75, 3.50140MU
3.50, 4.00150MV
4.00, 4.50160

Load Capacity

A few tire size codes also include the tire load capacity. The table below will help you determine the correct tire load code as per your needs.

47 = 386 lb. 

48 = 397 lb.

49 = 408 lb. 

50 = 414 lb. 

51 = 430 lb.

52 = 441 lb.

53 = 454 lb. 

54 = 467 lb.

55 = 481 lb.

56 = 494 lb. 

57 = 507 lb. 

58 = 520 lb.

59 = 536 lb. 

60 = 551 lb. 

61 = 567 lb. 

62 = 584 lb. 

63 = 600 lb. 

64 = 617 lb.

65 = 639 lb. 

66 = 661 lb. 

67 = 677 lb. 

68 = 694 lb. 

69 = 716 lb. 

70 = 739 lb.

71 = 761 lb. 

72 = 783 lb. 

73 = 805 lb.

74 = 827 lb. 

75 = 853 lb. 

76 = 882 lb.

77 = 908 lb. 

78 = 937 lb. 

79 = 963 lb. 

80 = 992 lb. 

81 = 1,019 lb. 

82 = 1,047 lb.

83 = 1,074 lb. 

84 = 1,102 lb. 

85 = 1,135 lb. 

86 = 1,168 lb. 

87 = 1,202 lb.

Tire Sizes Conversion

This table will help you to convert the tire code size into another measuring system.

FRONT

InchMetricAlphanumeric
2.50/2.7580/90MH90
2.75/3.0090/90MJ90
3.25/3.5100/90MM90
4.00110/90MN90
4.25/4.50120/80MR85
5.00/5.10130/90MT90

REAR

InchMetricAlphanumeric
4.00/4.50110/90 MN90
4.50/4.75120/80MP85
4.50/4.75120/90MP90
5.00/5.10130/90MT90
6.00/6.25150/80MV85
6.00/6.25150/90MV90

How to Read the Motorcycle Tire Size

1. Read the code engraved on the tire sidewall.

2. Determine the tire size format from the code.

3. Note all the factors that make the tire size code

4. Make sure you interpret the code correctly.

The most important tire size code factors are:

  • Aspect ratio
  • Construction code ( R or B)
  • Rim diameter size
  • Tire type code
  • Load capacity
  • Speed rating

5. You can also observe the tire to note whether it is TubeLess(TL) or TubeType(TT).

6. You can also look at the tire tread pattern to determine the correct tread pattern for yourself and the bike.

7. After reading all the codes and letters on the tire, you are now ready to determine the correct tire size and type.

Conclusion

Reading the tire size is not an easy task for everyone. However, if you wish to choose the best tire for your motorcycle this guide must have undoubtedly helped you. We hope you now know how to read motorcycle tire size and infer the tire size codes easily.