BMW 1 Series Brake Discs: Specs, Fitment & Wear Symptoms

On the 1 Series, what's commonly called "warped discs" is genuinely almost always uneven pad deposits, since cast iron is genuinely hard to warp.

Generation covered: this guide is for the third-generation 1 Series (F40, 2019–present), with particular focus on 2019–2023 registered examples now old enough for parts to be a common search. Check your logbook or VIN if you're unsure which generation you have.

Illustration for editorial purposes

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OEM Part Number: 34118848417

Accuracy note: confirmed for F20/F21 generation (2011-2019) standard trims — M135i/M140i performance models use significantly larger discs, so always confirm your exact trim and chassis number before ordering, since BMW's own parts department has confirmed a 340mm disc genuinely can indicate M Performance brakes even without other visual cues.

Front discs, standard trims (116i, 118d, 118i, 120d, 120i, 125d, 125i)	BMW OEM: 34118848417 — 312mm diameter, 24mm thickness, vented (also shared with related 2/3/4 Series models)
Rear discs, standard trims	Typically 300mm diameter, vented, around 20mm thickness
M135i/M140i front discs	340mm diameter, vented, 30mm thickness, 28.4mm minimum — a genuinely different, larger specification
Minimum thickness (BMW specification)	2.5mm below the disc's cast new thickness figure is a commonly cited wear limit — always check the specific minimum stamped or documented for your exact disc rather than assuming a universal figure.

BMW 1 Series Brake Discs: The Part That Pads Depend On

On the BMW 1 Series, discs and pads work as a pair, and neglecting one tends to accelerate wear on the other — which is exactly why worn discs so often get discovered during what was meant to be a routine pad change.

Before you buy: disc size and design vary by trim, engine size and whether your car has the standard or "sport" brake package. Always confirm against your VIN before ordering.

BMW 1 Series Brake Discs reference plate

BMW 1 Series Brake Discs: What They Do

Brake discs provide the surface the brake pads clamp against to slow the car, converting momentum into heat through friction. Larger, sportier trims of the 1 Series typically use bigger discs than standard versions to handle the additional heat generated by more aggressive braking.

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A Genuinely Important, Honest Clarification Worth Knowing — BMW 1 Series Brake Discs

If a vibration under braking has been diagnosed as warped discs, this is genuinely worth knowing: what's commonly described as "warped discs" is, in reality, almost always caused by uneven deposits of pad material on the disc surface, since cast iron itself is genuinely difficult to warp under normal driving conditions.

A genuinely alarming, honest account worth knowing: documented cases describe fast-fit chains replacing "warping" discs under warranty multiple times within less than a year, with owners suspecting the cheapest available parts were being used.

It's also genuinely worth knowing a useful fix worth trying: thoroughly cleaning the mating surfaces between the wheel hub and the disc, or better still fitting new hubs entirely, has been documented resolving this kind of persistent vibration.

BMW 1 Series Brake Discs: Wear Symptoms, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Brake Discs Guide for warning signs to watch for, confirming fitment against your VIN, and choosing a reliable aftermarket disc.

More BMW Brake Discs

The same part, covered across other BMW models.