What are marbles in F1?
Bits of worn tyre rubber that collect off the racing line and are very slippery to drive over.
Marbles are small pieces of shed tyre rubber that gather off the ideal racing line as a race goes on. They look like scattered pellets and offer almost no grip, so a driver who runs wide onto them can suddenly slide. Picking up marbles on the tyres also adds useless weight and can briefly reduce grip until they are cleaned off. This is why cars weave on an in-lap or after the finish — to clear rubber and pick up marbles for the post-race weigh-in.
Related strategy & the pit stop terms
- The undercut — Pitting for fresh tyres before a rival, then using the grip advantage to jump ahead once they stop.
- The overcut — Staying out longer than a rival on older tyres, then using clear track to pit later and emerge ahead.
- Box / "box, box" — The radio call telling a driver to come into the pits this lap; "box" comes from the German for the pit garage.
- Out-lap and in-lap — The out-lap is the lap leaving the pits on fresh tyres; the in-lap is the lap driven into the pits before a stop.
- Pit window — The range of laps in which stopping makes strategic sense given tyre life and the cars nearby.
Now you know the term — catch it live. See when practice, qualifying and the race start for the United States GP in your timezone, or browse the full 2026 F1 schedule.
Definition written in plain language from the current F1 sporting rules and common usage, current as of 14 August 2026. Unofficial; not affiliated with Formula 1.