1. MOTOR VEHICLE DEPARTMENT
WHEELS AND TYRES
MOTOR VEHICLE DEPARTMENT
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2. WHEELS
Wheels may seem a fairly simple component on a car but in fact, a good deal of design goes into them.
 Wheels are made of pressed steel, Aluminium or Magnesium alloy. Steel or Aluminium alloy are the most common.
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3. WHEEL DESIGN Drop centre design
Drop centre section
Drop centre design
Wheels are usually of a drop centre design on Motor Cars. This relates to the recess created in the area where the tyre sits that is used to allow the tyre bead to drop into during removal and refitting.
Semi-Drop centre Design
This is a two piece designed wheel rim that has a removable outer rim to enable ease of tyre fitment. It still has recess but this is shallower than the drop centre design. (Usually used on trucks due to large tyre sizes)
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4. RUN FLAT RIM
This design of wheel has additional recesses for the tyre bead to sit in to prevent the tyre coming off the rim when driven deflated.
 A second design has a removable steel or plastic band that fits over the drop centre recess to prevent the tyre bead falling into it should the tyre become deflated. A special design of tyre must be fitted to these wheels and unlike normal tyres; they can be driven on whilst deflated
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5. TYRES
All modern motor vehicles use a tyre filled with compressed air called a pneumatic tyre. There are two basic types of tyre construction and two methods of inflating them.
Tubed tyre: This is a tyre that requires a separate ‘inner tube’ to contain the compressed air used to inflate it.
Tubeless tyre: This tyre forms an airtight seal against the edge of the wheel and this contains the air used to inflate it.
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6. TYRE CONSTRUCTION
All tyres are made up of layers of casing plies and rubber. These layers can be applied in two ways:
 Cross-ply: This is where the layers are built up in an overlapping diagonally manner
 Radial-ply: In this case the layers are arranged so that the casing plies are at 90 to the tyre bead.
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7. TYRE CONSTRUCTION Bias belted & Braced tyres
Almost all road tyres used on modern vehicles will by either bias belted or braced. These are the terms given to the radial cord layers that go around the circumference of the tyre and provide the strength to resist enlargement when inflating. (Stop the tyre going tube shaped). Textile layers are called ‘bias belted’ and steel layers are called ‘braced’
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8. Marks
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9. REMOULD TYRES
Remould Tyres - Rarely use these days a remould tyre is a tyre that has had its worn tread removed and a new piece of tread moulded onto it. They can only be used on vehicles that use a low speed rated tyre.
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10. TREAD PATTERNS
The tread on a tyre provides the contact with the surface the car is driven on and will be tailored to various surfaces.
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11. RUN FLAT
The Run Flat is a development that will revolutionise not only the way the car is used but also the way it is made. If the absence of the spare wheel is a major opportunity for supersport car designers and developers, the elimination of the risk of a puncture will be a real destroyer of nightmares and certainly a huge personal safety factor of advantage to all motorists.
Sidewall Reinforced
Run flat tyres are designed to keep the tyre beads securely anchored to the rim flange area of the wheel even when operating at zero pressure.
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12. RUN FLAT Support Ring 05/09/06 kbuchanan
The system consists of four interdependent elements: wheel (rim), tyre, support ring and pressure loss or run-flat indicator. The principle feature of the Pax System is the way the tyre is anchored on the rim. A conventional tyre is held in place mainly by its pressure but the Pax System achieves a secure seat of the tyre bead on the rim with the help of a wedge shaped rubber element inside the casing that clamps into the rim. Any force working on the tyre only drives the wedge more firmly between rim and bead wire, thus ensuring the secure seat of the tyre on the wheel independently of the pressure inside the tyre.
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13. TYRE VALVE
This valve is commonly also called a Schrader Valve and provides the means of inflating and deflating the tyre. Internally they are the same as a Mountain bike tyre valve, having a removable inner core with a central pin to release pressure when pressed. 
Valves should be replaced when replacing a tyre and are pulled into position from the inside of the wheel well.
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15. INNER TUBES
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16. WHEEL LOCATING AND SECURING DEVICES
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17. Wheel Fixings
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18. Wheel fixings
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19. ROUTINE MAINTENANCE EQUIPMENT
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20. REPAIRABLE AREA
The repairable area T is defined as a percentage of the tyres nominal section width and is dependant on the type and size of the tyre.
This chart shows the limitations that apply to the number of repairs allowed to a tyre and also the limitation on the size of the injury
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21. REPAIR TOOLS
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