Vehicle technology, tyres and maintenance
This domain checks the small checks that keep a bike legal and predictable: tyre condition and pressure, chain, brakes, fluids and lights. The exam expects concrete figures, not vague care.
Tyres
- Legal minimum tread depth is 1.6 mm in the main grooves; on a motorcycle replace at 2–3 mm, front first.
- Set pressures cold, to the handbook figure, plus what the maker specifies for pillion and luggage (often about +0.2 to +0.3 bar at the rear).
- Inspect for cuts, bulges, stones in the tread, sidewall cracks and one-sided wear. A bulge means the tyre is scrap.
- The DOT number gives week and year of manufacture; rubber hardens after roughly six years.
- Never mix radial and bias-ply tyres, and keep to the type approved for the machine.
Chain, brakes, fluids
- Chain free play is typically 20–30 mm; too tight destroys bearings, too loose can jump the sprocket. Lubricate when warm.
- Brake pads have wear marks; brake fluid absorbs water and is changed about every two years. A spongy lever means air in the system.
- Before a long ride check lights, indicators, horn, mirror, spokes, fork seals and steering-head bearing play.
Worked example
Handbook: 2.5 bar front, 2.9 bar rear, solo. After an hour of motorway you measure 2.8 and 3.2 bar and think the tyres are over-inflated. They are not - riding heat adds roughly 0.2–0.3 bar. Bleeding air out leaves you riding on under-inflated tyres that run hotter and grip worse. Measure cold next morning and set the pressures for the load you will actually carry.
Traps that cost marks
- Adjusting pressure with hot tyres, or "correcting" it downwards.
- Reading the wear indicator as a target rather than a limit.
- Riding a stored machine on years-old, hardened rubber.
- Cleaning the chain with the engine in gear and the rear wheel turning.