Please Note

This information is only a guide and if in doubt about any specific fitting please consult and follow manufacturers recommendations

Running in

A New tyre will need at least 50 miles running in before it gives it best and for the first mile or so can be lethal if thrown hard into a bend for example.
The best tyre in the world will not give it performance until it is up to temperature.

Specification on Side Wall

Moulded / written into the side wall of a tyre is all its specification. In short it tells you anything that you may need to know about your tyre.

Example BT45F 110/80-17 57H
Manufacturers Code BT45
F Front
110 Width in millimetres
80 Height of the sidewall as a percentage of the width. Aspect ratio.
17 The diameter of the inner rim in inches
57 Load Capacity of Tyre
H Speed Rating

Load Capacity

Index Capacity in Kilos
62 265
72 355
82 475

Speed Ratings

These initially increase in 10 KPH increments.

Rating KPH MPH
F 80 50
G 90 56
J 110 69
L 120 75
M 130 81
N 140 87
P 150 93
Q 160 100
R 170 106
S 180 112
T 190 119
U 200 125
H 210 131
V 240 150
Z 240 Plus 150 Plus

E4 Mark

Any tyre sold in the EEC should have a type approval mark and number starting with E4. This shows that it has passed the high standards of the European regulatory authorities.

Mixing Radial and Ply / Belt Tyres

Boths tyres Radial or Radial as back tyre only.

Mixing and Choice of Tyres

In some countries it is is illegal to run different manufacturers of tyres on the front and rear.
Tyre manufacturer are often very specific in their recommendations for fitting on a specific vehicle.
A tyre of the correct size and speed rating will often not be recommend because it has not been tested on a particular motorcycle.
Vehicle manufactureres can also be very specific about their tyre recommendations.
To state the obvious, different tyres and in different combinations suit different riding styles, conditions, temperatures, tastes and needs.

Sufficient Clearance

A good clearance between the tyre and all motorcycle parts such as Guards is important as Heat and Centrifugal force will increase diameters during use.

Directional Arrows

Some tyres are made to run in only one direction and this is shown by a directional arrow moulded into the tyre wall.

Size Conversion Table

Metric Inch
80/90 2.75, (3.00)
90/90 3.00, (3.25), (3.60)
100/90 3.25, (3.50), 3.60
110/90 3.50, (3.75), 4.10
120/90 4.00, 4.25, 4.25/85, 4.60
130/90 4.50, 5.00, 5.10
140/90 5.50

Please note: Values given in brackets are theoretically possible, but not recommended.


New tyre have little grip for the first few miles. Go gentle for a few miles !