What is the purpose of tyres?
Grip
Steering
Braking
Tread disperses water in adverse conditoin
What does aquaplaning mean?
When a layer of water builds between a vehicle’s tyres and the road surface, leading to a loss of traction and control, often resulting in the vehicle sliding uncontrollably
What are the tyre parts?
Beads
Body plies
Tread
Sidewall
Belts
Liner
What do the beads contain?
Rings of steel wire = provides strength and stops tyre coming off the rim
What wraps around the beads?
Body plies = fabrics and cords wrapped around the beads
What is the purpose of the belts?
Used to strenghten body plies and tread
Number and material of belts = important
What used to be found inside tyres?
Inner inflatable tube
The tube inflation pressure allows the tyre to keep its shape, while supporting the vehicle’s weight.
What replaced internal inflatable tube?
Liner = layer of rubber bonded inside tyre
Why are internal inflatable tubes not used anymore?
Harder to fit
Deflate quicker
Not as reliable
Compare cross-ply to radial ply tyres
Cross ply = 45 degree to bead (aka diagonal bias tyres)
—Strong sidewall needed in HGV
—Contact patch varies
Radial tyres = 90 degrees to the bead (perpendicular)
—For lightweight vehicles so they can go around corners
—Contact patch remains more constant because the sidewall is flexible
What is the purpose of tread wear bars?
Indicate how worn car tyres are
What is the limit of tread wear bars?
2mm
What does TPMS stand for?
Tyre Pressure Monitoring System
Where is active TPMS found?
The sensor is found in the wheel itself, attached to the Schrader valve
How does active TPMS work?
By using a battery-powered sensor in each wheel that measures tire pressure and temperature, transmitting the data wirelessly to the vehicle’s control unit.
How does passive TPMS work?
Calculares through wheel speed sensors that measure rolling circumference = ABS
What does the TMP light indicate when it is ON?
Inidcates incorrect pressure = either too high/low
What does TMP light indicate when its FLASHING?
Fault with teh TMPS itself
What are the advantages of steel wheels?
Cheap to produce
Easier to repair than alloy wheels
What are the advantages of alloy wheels?
Lighter than steel wheels
Better heat condution
What are the qualities of space saver wheels?
They are narrower than normal wheels
Speed restriction of 50mph
Describe valve components
Valve stem
Spring loaded insert
Washes
Valve core = allows air to enter tyre
Valve cap keeps out dust and helps keep air in
What is the purpose of wheel fixings?
Lug studs and nuts attah the wheel to the hub
Name two wheel fixings
Lug studs
Lug nuts
