Tyre size designation can be found on the tyre's sidewall with information about tyre:

  1. » Tyre width in inches or mm
  2. » Aspect ratio – ratio of height to width
  3. » Construction type
  4. » Speed index - Maximum allowed speed
  5. » Rim diameter
  6. » Load index - Maximum load capacity

1. Radial motorcycle tyres - designation in mm

Metric tyre size designation is the most common designation system. For example:

Motorcycle tyre size designations

Designation: 190/50 ZR 17 M/C (73W) TL

Let's see what each symbol means.

195
Tyre width in Millimeters (mm)
/50
Aspect ratio, ratio of height to width (50 : 100).
ZR
Radial construction.
17
Rim diameter in inches.
M/C
For motorcycles only, to prevent mixing with car tyres. Motorcycle tyres must not be mounted on car rims.
(73)
Load index. See the load index table.
(W)
Speed index > = 270 km/h (allowed higher speed than 270 km/h). You may lookup the value in the speed index table.
TL
Tubeless tyre.

Motorcycle tyre size designations section

2. Bias ply (cross ply or diagonal ply) - designation in mm

Designation: 130/90 - 18 M/C 69 R TT

Symbols meaning:

130
Tyre width in Millimeters (mm).
/90
Ratio of height to width (90 : 100).
-
Bias ply construction.
18
Wheel diameter in inches.
M/C
For motorcycles only, to prevent mixing with car tyres. Motorcycle tyres must not be mounted on car rims.
69
Load index – maximum permitted load. See the load index table.
R
Maximum permitted speed (R = 170 km/h). You may lookup the value in the speed index table.
TT
Tube type.

3. Bias ply - designation in inches

Designation: 4.00 - 18 M/C 64H TL

Symbols meaning:

4.00
Tyre width in inches.
-
Bias ply construction.
18
Wheel diameter in inches.
M/C
For motorcycles only, to prevent mixing with car tyres. Motorcycle tyres must not be mounted on car rims.
64
Load index – maximum permitted load.
H
Maximum permitted speed (H = 210 km/h).
TL
Tubeless tyre.

4. Bias ply – alphanumeric designation

Designation: MT 90-16 T 71H TL

Symbols meaning:

M
Motorcycle.
T
Tyre width symbol, T = 5.10 inches.
90
Ratio of height to width (90 : 100).
16
Wheel diameter in inches.
T
Rim contour.
71
Load index – maximum permitted load.
H
Maximum permitted speed (H = 210 km/h).
TL
Tubeless tyre.

5. Bias belted – designation in mm

Designation: 180/55 B 17 M/C 73Q TL

Symbols meaning:

180
Tyre width in mm.
/55
Ratio of height to width (55 : 100).
B
Symbol for construction type – bias belted.
17
Wheel diameter in inches.
M/C
For motorcycles only, to prevent mixing with car tyres. Motorcycle tyres must not be mounted on car rims.
73
Load index – maximum permitted load.
Q
Speed index, maximum permitted speed (Q = 160 km/h).
TL
Tubeless tyre.