Match it to the duty: organic for light and quiet use, semi-metallic for load and heat, ceramic for low dust and noise, sintered only where heat is extreme.

Organic and low-metallic compounds are quiet, kind to discs and comfortable cold. They fade first under sustained heavy braking.

Semi-metallic pads handle far more heat and give stronger bite when hot, which suits loaded commercial vehicles and hilly routes. They are noisier and wear discs faster.

Ceramic compounds produce noticeably less dust and noise and suit vehicles where wheel cleanliness matters, with good but not extreme heat capacity.

Sintered metal pads tolerate very high temperatures and are poor when cold, which makes them a specialist rather than a general choice.

For a mixed fleet, pick one compound per duty profile rather than per vehicle - it makes wear rates and driver feedback comparable.

It is a controlled series of moderate stops that lays an even transfer layer of friction material onto the disc - and skipping it causes most 'warped disc' complaints.

Friction between pad and disc works partly through a thin film of pad material deposited on the disc face.

Laid down evenly, it gives smooth, consistent braking. Laid down unevenly - by a hard stop from new, or by holding the brake while the pads are hot - it produces thickness variation.

That variation is felt as a pulsing pedal and is almost always diagnosed as a warped disc, when the disc is geometrically fine.

The procedure is a sequence of moderate decelerations from moderate speed with cooling between, then avoiding a stationary hold while hot. Manufacturers publish their own.

It takes a few minutes on the road test and prevents a comeback, which makes it one of the cheapest quality steps available.

Vibration between pad, caliper and disc - usually cured by the hardware, the shims and the right lubricant rather than by a different pad.

Squeal is a high-frequency resonance. It has little to do with braking performance and a great deal to do with how the pad is constrained.

Anti-squeal shims on the backing plate damp the resonance and should never be omitted or reused if damaged.

The abutment clips and slides supplied with the kit set how the pad sits. Reusing old, corroded hardware is the single most common cause of noise after a pad change.

A thin film of the correct high-temperature brake lubricant on the backing plate and contact points - never on the friction face - completes it.

Persistent squeal after all of that usually indicates the compound is wrong for the duty, or a glazed pad and disc that need deglazing.

Manufacturers publish a minimum friction thickness, and the wear indicator is set to warn before it - but measure rather than rely on the warning.

The minimum is a thickness of friction material above the backing plate, and it exists because thin material overheats and can separate.

Mechanical wear indicators are a sprung tab that contacts the disc and squeals. They are effective and are frequently ignored by drivers.

Electrical sensors trigger a dashboard warning and are more likely to be acted on, though they only monitor the corners where they are fitted.

Pads on the same axle rarely wear evenly, especially if a caliper is sticking, so both sides need measuring rather than one.

For fleets, recording pad thickness at every service turns replacement into a planned job rather than an off-road event.

Not always, but a disc at or near its wear limit should be replaced with the pads, and a heavily scored or glazed disc will ruin new pads.

Discs and pads wear together, and the disc's minimum thickness is the deciding number.

If the disc will fall below the minimum before the new pads are worn out, it is replaced now rather than at the next pad change.

A scored disc gives the new pad an uneven surface to bed against and will produce noise and poor performance.

A glazed disc - shiny and hard from overheating - will not take a transfer layer, and either needs deglazing or replacing.

Fitting new pads to a good disc within its limits is entirely legitimate and is normal practice on vehicles that get their pads changed on schedule.

Dust is friction material and disc material worn away - the amount is set by the compound, and low-dust formulations exist specifically for it.

Semi-metallic compounds shed the most, and much of what is visible on the wheel is iron worn off the disc rather than the pad.

Ceramic and low-metallic compounds produce noticeably less, and what they do produce is lighter coloured and less inclined to bond to the wheel.

Dust that has been baked onto a wheel by heat is corrosive to the finish, so it is a genuine complaint on vehicles where appearance matters.

The trade is usually heat capacity: the lowest-dust compounds are not the ones to fit to a fully loaded vehicle working in hills.

Where dust is the driver of the choice, say so when specifying, because it is a legitimate requirement rather than a cosmetic one.

It is duty, not distance - urban stop-start work can consume a set in a fraction of the life the same pads give on long runs.

Every stop converts the vehicle's energy into wear, so the number of stops matters far more than the kilometres between them.

Load multiplies it. A fully laden vehicle puts far more energy into the friction material at every application.

Terrain matters as much: descents are sustained braking, and sustained braking is what heats and wears pads fastest.

Driving style is the largest single variable, which makes pad life a useful driver indicator when it is tracked by vehicle and by driver.

For that reason a fleet should predict pad life from its own history on that duty rather than from any published figure.