In short. Bedding in, also called burnishing or breaking in, is the first use of new pads and discs, done so that the pad wears flat against the disc and leaves an even, thin film of its own material on the disc face. The makers do not agree on how. Some documents ask only for gentle braking over the first few hundred kilometres (the brake maker Brembo says about 300 km, BMW of North America 300 to 400 miles); others publish an active routine, such as Tesla's six firm slow-downs from 80-90 km/h to 15 km/h, 30 seconds apart. Every routine we read shares two rules: slow down without stopping, and never sit at a standstill with your foot hard on hot brakes. Follow the sheet that came with your pads first; in the UK and EU, the approval rules require the box to contain one.
What bedding in actually does
Two things happen when new pads meet a disc. First, the surfaces have to match: BMW's service bulletin to its North American dealers says that new discs and pads "need some mileage in order to adapt to each other", and that until then the microscopic roughness of the new surfaces can make them squeak (BMW SIB 34 05 20, 15 June 2020). Second, pad material is deposited on the disc. The StopTech engineers' white paper gives bedding two objectives when both parts are new: to heat pads and discs in a controlled way "so as to transfer pad material evenly onto the rotors", and to mature the pad by cooking the binding resins out of its surface (StopTech and scR motorsports).
That film is why the order matters. A pad working against an even layer of its own material grips consistently. A pad working against a patchy layer does not, and the patches show up as uneven thickness on the disc. BMW's bulletin says vibrations on higher-mileage cars are "generally caused by thickness variations of discs and/or pads", which is the judder people often call a warped disc.
A third effect is temporary and worth knowing before you drive off: new pads brake less well. Polestar's manual says the braking effect is not adapted until the pads and discs are broken in over a few hundred kilometres, and tells you to compensate by pressing the pedal harder (Polestar 2 manual). StopTech warns of the "longer stopping distance" of pads that are not yet bedded. Leave more room in front.
Before you start: is the car safe to drive?
If you changed the pads yourself, the car was lifted: it must have stood on axle stands, never on the jack alone (changing a wheel safely). The wheels go back on with the car maker's torque, in a cross pattern, checked again after a short drive (wheel nut torque). Press the pedal several times while the car is still parked: after new pads go in, the pistons have to come back out to meet them. If the pedal stays soft, sinks or the brake warning light is on, do not drive; have the brakes checked before you take to the road.
Tesla also asks you to check the tyre pressures before its burnish routine (Tesla). Tesla asks for a straight road with little or no traffic, in a place where such manoeuvres are legal; GM's bulletin adds dry pavement, and StopTech dry conditions on a track or other controlled place. Nobody should be close behind you.
Nine published procedures, side by side
This table is our own record of what each document says, read on 16 October 2026. Speeds are converted where the source gives one unit only.
| Source | For | Applications | Speeds | Firmness | Between applications | Afterwards |
|---|---|---|---|---|---|---|
| Tesla, Model 3 guide | New pads or discs; also high-pitched squeal | 6 | 80-90 km/h (50-55 mph) down to 15 km/h (10 mph) | Steady, moderate | At least 30 seconds | Book a service if the noise persists |
| BMW of North America, SIB 34 05 20 | New discs and pads | No routine | Normal driving | "Rather gently" if traffic allows | — | Break-in usually 300-400 miles (480-640 km), up to 1,000 miles (1,600 km) |
| GM 22-NA-026, Corvette with performance brakes | Pulsation, noise, pitting from corrosion | 10, then optionally 10 more | 100 to 50 km/h (60 to 30 mph) | 0.4 g; optional second pass at 0.7 g | At least 0.5 km (0.3 mi) | — |
| GM 17-NA-280, Camaro ZL1 track package, track burnish | "Fog horn" noise at very low speed, linked to the surface treatment of new rotors | 25 medium, then hard ones (up to about 25), then 25 medium | 100 to 50 km/h; hard ones 100 to 25 km/h | 0.4 g; hard ones 0.8 g without triggering ABS | At least 1 km (0.6 mi) | About 15 km (10 mi) at 100 km/h without braking, between the stages |
| Polestar 2 manual | New pads and discs | No routine | Normal driving | Press harder to compensate | — | A few hundred kilometres |
| Brembo | New pads and discs | No routine | Normal driving | Effective but brief and gradual; no sharp or violent braking | — | About 300 km; watch for vibration and noise |
| EBC, street pads | Coated street pads | No routine | Normal driving | Cautious | — | Coating works for about 100 miles (160 km); for one street grade, cautious driving for 300-400 miles (480-640 km), especially with new rotors; no aggressive use before 300 miles |
| Hawk, street pads | New pads, new or used discs | 6 to 10, then 2 to 3 hard | 30-35 mph (48-56 km/h), then 40-45 mph (64-72 km/h) | Moderate, then hard | Not stated; "do not drag brakes" | 15 minutes to cool |
| StopTech, street-performance pads | Performance systems | 10 per set, two sets | 60 to 10 mph (97 to 16 km/h) | 80-90% of the deceleration that locks the wheels or wakes the ABS | None: back to back | Cool by driving without stopping, then the second set |
Sources: Tesla, BMW, GM 22-NA-026, GM 17-NA-280, Polestar, Brembo, EBC, Hawk, StopTech.
Three things stand out. The documents split into two families: a gentle running-in over a few hundred kilometres (Brembo, BMW, Polestar, EBC for street pads), and an active routine of a few dozen firm slow-downs (Tesla, Hawk, GM, StopTech). Nobody in the second family brings the car to a halt between applications except Hawk's street pads, whose stops start from low speed. And the hard, near-ABS routines come from documents about performance or track brakes: GM's bulletins say they are written for professional technicians, not for do-it-yourselfers, and StopTech recommends a track or other controlled place and says it does not condone high speeds on public roads.
How much heat each routine puts in
Bedding is a matter of heat, and heat comes from the car's speed. This is our own arithmetic: the energy a brake turns into heat during one slow-down is half the mass times the difference of the squared speeds, 0.5 × m × (v1² − v2²). We take an invented car of 1,800 kg and ignore air drag, rolling resistance and, on an electric car, the share taken by regenerative braking, so these are upper bounds.
| Routine | Per application | Number | Total |
|---|---|---|---|
| Hawk street pads, stops from 30-35 mph, then from 40-45 mph | 162 to 220 kJ, then 288 to 364 kJ | 6-10, then 2-3 | 1.5 to 3.3 MJ |
| Tesla, 80-90 to 15 km/h | 429 to 547 kJ | 6 | 2.6 to 3.3 MJ |
| GM 22-NA-026, 100 to 50 km/h | 521 kJ | 10 | 5.2 MJ |
| StopTech, 60 to 10 mph | 630 kJ | 10 per set | 6.3 MJ per set |
| FMVSS 135 test burnish, 80 km/h to rest | 444 kJ | 200 | 89 MJ |
From 80 to 100 km/h, one slow-down puts in roughly half a megajoule; Hawk's lower-speed stops put in a third to two thirds of that. What differs is how many follow one another before the brakes cool. Tesla leaves 30 seconds between six applications. StopTech chains ten without a pause, on purpose, so that the pads reach the temperature at which they transfer material and lose their resins; it says the friction "will seem to gain slightly" and then fade around the fifth stop, and that this "green fade" does not mean the job is done. That is why a performance routine needs a cooling drive afterwards, and why it belongs on a closed road.
The classic mistake: stopping and holding hot brakes
After a series of firm applications, the pads and discs are at their hottest. If you then come to a full stop and keep your foot on the pedal, the pad sits pressed against one patch of hot disc. StopTech is explicit: the car "should not be brought to a complete stop, with the brakes still applied", because this "risks the non-uniform transfer of pad material onto the friction surface". That patch is the start of the uneven deposit described above.
Hawk's reminders for its motorsport pads say not to engage the pedal while the car is stopped at any time after the break-in. BMW's dealer bulletin gives the same advice for everyday driving: after severe use, "try to avoid applying the brake pedal while waiting at a traffic light", and shift into P instead.
Safety comes first. If you are on a slope or in traffic and the car would roll, hold it: with P or the parking brake where that is safe, otherwise with the pedal. Plan the route so the routine ends with a cooling run of several minutes at a steady speed, with little or no braking, before you have to stop. Hawk asks for 15 minutes of cooling for street pads and about 20 minutes, or until the discs are cool to the touch, for motorsport pads.
A routine that respects every source we read
There is no universal procedure, and the sheet supplied with your pads, or the car maker's instructions, takes priority over this one. If neither gives a routine, the points common to the documents above are:
- Drive gently for the first few kilometres, leave more room in front, and expect the pedal to need more pressure (Polestar, StopTech).
- On a legal, quiet, straight road in the dry, make about six to ten slow-downs from 80-90 km/h (50-55 mph) to about 15 km/h (10 mph), with steady, moderate pressure: firm enough to feel, never enough to wake the ABS (Tesla; GM's medium applications at 0.4 g are of the same order).
- Do not stop between them. Accelerate again and leave 30 seconds or more, or half a kilometre, before the next one (Tesla, GM).
- Cool down by driving for several minutes with little or no braking, then avoid holding the pedal at your first stop (StopTech, Hawk, BMW).
- Then drive normally but without violent braking for the next few hundred kilometres: about 300 km for Brembo, 300 to 400 miles for BMW, no hard use before 300 miles for EBC.
For track pads, follow the pad maker's track procedure; EBC and Hawk publish separate ones for their race compounds, and EBC warns that, in the EU, using a race pad without road approval on public roads is illegal.
What the official rules say
No rule in the UK, the US, Canada or Australia that we found tells a driver how to bed in brakes. The rules describe how brakes are bedded before the official measurements, and in Europe they make the fitting instructions compulsory.
UK and EU: UN Regulation No. 90. Replacement pads for cars must carry an approval under this regulation. In UK law, Article 7 of Regulation (EU) 2015/166 as retained says that "with effect from 1 November 2014, UNECE Regulation No 90 shall apply for the purposes of the sale and entry into service of new replacement brake lining assemblies" for cars of up to 3.5 tonnes whose vehicle type received its approval on or after 7 April 1998 (legislation.gov.uk). Regulation No. 90 then says, in paragraph 6.1.4, that "each package shall contain fitting instructions" in the language of the country where it is sold. For its tests on a car, Annex 3, paragraph 1.1.2.2, beds the pads in this way: "Perform a minimum 50 km driving distance and at least 100 brake applications at varying decelerations (at least between 1 m/s² and 5 m/s²) with initial speeds between 50 km/h and 120 km/h", reaching 250 to 500 °C at the disc surface at least three times and never more than 500 °C (UN Regulation No. 90, Revision 3, 17 February 2012). Amendment 9, in force since 4 January 2023, does not change that paragraph; we have not checked every amendment in between.
US: FMVSS 135. The test sequence for new light vehicles starts with a burnish set out in S7.1.3: test speed "80 km/h (49.7 mph)", a constant deceleration of "3.0 m/s²", "200 stops", each started at 100 °C or less, the next one after the brakes cool to 100 °C "or the distance of 2 km (1.24 miles), whichever occurs first" (eCFR, 49 CFR 571.135, up to date as of 14 October 2026). Our arithmetic: 200 intervals of at most 2 km is at most 400 km of driving, the same order as the 300 km Brembo gives and BMW's 300 to 400 miles for gentle running-in. A deceleration of 3.0 m/s² is about 0.3 g, a little gentler than GM's medium application.
For Canada and Australia we did not read a text that addresses bedding; the pad's instructions and the car's handbook are the documents to follow there too.
When bedding did not work
The signs, from the documents above: a vibration through the pedal or the steering wheel under braking, which BMW links to thickness variation of the disc; a squeal that does not fade, which Tesla treats with its burnish routine and then with a service visit if it persists; and a contact band that does not cover the disc face, which EBC asks you to check before relying on track pads. StopTech says the transfer layer can be re-established by repeating a series of stops.
A vibration felt at speed without braking is a different fault: start with wheel balancing. If the discs are scored, cracked or below their minimum thickness, no routine will help: have them checked before you take to the road.
Frequently asked questions
What does "bedding in brake pads" mean?
It is the first use of new pads, which wears them flat against the disc and lays an even film of pad material on it. Brembo, Tesla and GM call the same thing bedding in, burnishing or break-in.
Do new brake pads need bedding in?
They need a running-in period in every document we read. Some ask only for gentle driving (Brembo, about 300 km; BMW, 300 to 400 miles); others publish an active routine (Tesla, Hawk, GM). The sheet in the box comes first.
Should I bed in pads and rotors together?
When both are new, yes: the BMW bulletin and StopTech describe the adaptation of new surfaces to each other. StopTech says new discs with used pads need one set of stops, and new pads need two in its performance routine.
How many stops does it take?
Tesla says six; Hawk six to ten plus two or three hard ones; GM ten or twenty on the Corvette bulletin, and up to about seventy-five on the Camaro ZL1 one; StopTech ten per set, two sets. The official test rules use 100 (UN R90) or 200 (FMVSS 135).
Can I come to a full stop during bedding in?
Avoid it with hot brakes and the pedal held. StopTech says it risks an uneven transfer of pad material; Hawk and BMW say not to hold the pedal at a standstill after hard use. If the car could roll, hold it safely first.
How long before I can brake hard?
EBC says not before 300 miles for its street pads; Brembo asks for no sharp or violent braking over about 300 km. In an emergency, brake as hard as you need.
Does an electric car need bedding in?
Tesla publishes a burnish routine for its cars after new pads or discs. On an electric car, part of each slow-down is taken by regeneration, so the friction brakes get less heat than our calculation shows.
Is bedding in a legal requirement?
No text we read requires a driver to do it. UN Regulation No. 90 requires fitting instructions in every box of replacement pads sold under it, and both R90 and FMVSS 135 bed the brakes before testing them.
If you are changing wheels as well as brakes, our guide to brake caliper clearance explains what has to fit over the calipers. Onyx Forged does not recommend a size or an offset: we make made-to-order forged wheels, designed to JWL/VIA standards, for the car you describe. See the catalogue.
Sources
- Carmakers: Tesla, Burnishing the Brakes (Model 3); BMW of North America, SIB 34 05 20, brake noise, 15 June 2020; GM bulletin 22-NA-026, October 2024; GM bulletin 17-NA-280, July 2023; Polestar 2 manual, maintenance of the brake system.
- Brake makers: Brembo, indications and bedding in; EBC, how to bed in your brakes; Hawk Performance, how to; StopTech and scR motorsports, pad and rotor bed-in and Centric's 2018 copy.
- Rules: UN Regulation No. 90, Revision 3 and Amendment 9; Regulation (EU) 2015/166 as retained in UK law, Article 7; FMVSS 135, 49 CFR 571.135.
All pages were read on 16 October 2026.
The Onyx Forged design office.