A
ABS
An Anti-lock Braking System is a system that prevents the wheels from locking up when braking so they don't lose grip. The system works by partially releasing the brakes as soon as the wheels begin to lock, so they don't slip (lose grip). The system increases overall braking effectiveness.
ACT
Michelin Adaptive Casing Technology
The rigidity of the tyre carcass adapts to the camber angle. As such, depending on the camber angle, the tyre changes gradually from a soft crown for stability on straight stretches to more rigid shoulders according to the angle of the bike. This ensures optimal cornering.
ADT
Amplifed Density Technology A high density, more rigid carcass for better handling and feedback. Aramid fibre crown plies towards the rear of the tyre bring together durability and a lightweight build for perfect stability even at high speeds.
Air chamber
An inflatable rubber tube that fits between the wheel rim and the tyre.
Aquaplaning
A loss of grip at high speeds caused by a film of water between the tyre and the road, creating a slippery surface.
B
Balance
Good balance means that the tyre/wheel mass is well distributed across its rotational axis.
BibMousse
The BibMousse replaces air chambers inside motorcycle tyres. It is usually used on off-road, motocross, trial, MX, Enduro tyres etc. Once advantage of the BibMousse is that it can't be punctured because it is solid, nor do you need to check the tyre pressure.
Bore
The diametre of a cylinder
C
Carcass
The internal part of the tyre that makes up its structure. This is the part that absorbs all of the forces applied to the tyre. It is made from plies of steel cables and fabric covered by a belt and then the tread and sides.
Calendering
An airtight rubber compound covering for tyres without an air chamber i.e. Tubeless tyres.
Contact patch
Also known as the tyre print, this is the contact area between the your tyre and the road.
D
Diameter
When we talk about tyre diameter, we're always referring to the inside diameter of the tyre, i.e. the diameter of the wheel rim. It is measured in inches (1 inch = 2.54 mm).
DOT
The acronym of the United States Department of Transportation. If you see this stamped on the side of the tyre you know that it has been approved for use by this organisation.
E
Engine displacement
Engine displacement refers to the engine's capacity in CCs or cm3. Generally speaking, engine displacement is an important factor in determining the power of your bike's engine.
F
FIM
An acronym indicating that the tyre has been approved by FIM for Enduro use (tread depth of 13mm).
Front/Rear
A tyre that can be safely fitted to the front or rear of your motorcycle.
H
Hard
Difficult terrain that requires harder rubber.
I
Inner liner
An inner liner is a layer of a synthetic rubber compound, the modern equivalent of an air chamber, which is designed to keep the tyre airtight.
L
LR
Low rolling resistance tyres that decrease the rolling effort required.
Load index
A numerical index that indicates the maximum weight that the tyre can withstand when inflated to the recommended pressure.
M
M+S
An abbreviation of the term "mud and snow", which is used specifically for winter tyres to indicate that they may be used on this kind of terrain.
N
NHS
Not for Highway Service i.e. Not approved for the road.
P
Ply
A layer that makes up the tyre belt.
S
Sand
Tyres suited for use on sandy tracks
Sculpting
Refers to the tyre's tread pattern
Section height
The height of the tyre from the crown of the tread to the bottom of the tyre bead.
Section width
The distance between the tyre's sidewalls
Shoulder
The external part of the tyre tread that joins to the sidewall of the tyre.
Sidewall
The external wall of the tyre between the tread shoulder and the tyre bead. It protects the tyre from impacts (pot-holes, cobblestones…). This part of the tyre is made in durable rubber and it's where you'll find all of the tyre's essential information.
Sipes
Special slits cut into the tyre's contact surface with the road. They improve road holding properties when the surface is less than ideal (rain, black ice, snow).
Slick
Smooth tyres
Soft
Mixed or soft terrain requires soft rubber
Special slits cut into the tyre's contact surface with the road. They improve road holding properties when the surface is less than ideal (rain, black ice, snow).
Speed rating
A numerical rating that indicates the maximum speed that the tyre can withstand.
Structure
Refers to the make-up of the plies that form the tyre's carcass
Supersoft
Very soft rubber suited for use on soft terrain
T
Tyre bead
Part of the tyre that fits against the wheel rim.
Tyre tread
The external part of the tyre that is in contact with the road. Its role is to ensure grip in all conditions (dry, wet…) as well as enabling precise riding. Since this part of the tyre inevitably gets worn down, it needs to be as hard-wearing as possible.
Tyre print
The part of a tyre that is in contact with the road (also known as the contact patch).
Tread grooves
The term tread grooves refers to the space between two blocks of tyre tread.
Tube Type (TT)
A tyre with an air chamber.
Tubeless (TL)
A tyre without an air chamber. Airtightness is achieved by using an inner liner in direct contact with the tyre carcass.
U
Unusual wear
Abnormal tyre wear that may result from the wheels being unbalanced, or be due to poor suspension or a range of external factors, etc...
V
Valve
A component that regulates the entry of air into the tyre. It also prevents air from escaping from the tyre and prevents dust from getting inside the tyre.
Valves can be found on the air chamber for tyres that have one, or on the wheel rim for tubeless tyres.
W
WET
Tyres suited for use on wet roads.
Wear
Visible damage and deterioration of the tyre.
Wheel
Composed of a wheel rim and a disk.
Wheel rim
The circular metallic part of the wheel onto which the tyre is placed.
