studded tyre

A studded tyre is a winter tyre embedded with small metal pins, typically made of tungsten carbide or steel, that protrude from the rubber surface. These studs, usually 6 to 8 millimetres long and 4 to 5 millimetres in diameter, penetrate the ice surface directly rather than relying on friction alone. The rubber compound itself remains pliable at temperatures well below 0 degrees Celsius, staying elastic where standard summer rubber hardens and loses grip.

Stud patterns vary by manufacturer and tyre size, but most winter tyres carry 80 to 120 studs per tyre depending on width. The studs are pressed into pre-drilled holes in the tread block during vulcanisation or inserted post-cure. Dual-studded designs place two studs per hole for high-risk driving conditions, though this increases wear and road damage. Stud materials matter: tungsten carbide lasts longer than steel but costs more; soft steel studs are cheaper but wear faster and can be lost on long journeys.

Where studded tyres excel and fail

On packed ice and rutted snow, studded tyres outperform non-studded winter tyres by 20 to 30 percent in stopping distance and grip. On wet roads above 4 degrees Celsius or on bare asphalt, however, studs provide no advantage and actually reduce traction by reducing the rubber contact patch. The studs increase rolling resistance, worsen fuel economy by 5 to 10 percent, and generate noise from the metal striking pavement. They also damage road surfaces faster than conventional tyres, which is why many regions restrict or ban them during warmer months or on newer low-friction road treatments.

Stud loss is a common failure mode. As the rubber wears and the holes enlarge, individual studs vibrate loose and fall onto the road surface. A tyre that loses more than 30 percent of its studs loses measurable performance. Vandalism and impact damage can accelerate loss. The rubber surrounding each stud also tends to tear or chunk out around the hole, reducing structural integrity. Studded tyres typically require replacement at 3 to 5 millimetres of remaining tread depth rather than the 1.6 millimetre legal minimum.

Many European and North American jurisdictions permit studded tyres only during winter months (typically November to March in northern climates), requiring seasonal changeover. Some regions forbid them entirely on concrete or modern porous asphalt. Despite these restrictions, studded tyres remain standard in Scandinavia, Russia, and other cold-climate markets where ice roads and extreme winter conditions dominate. Countries like Germany and much of southern Europe have largely moved to studless winter compounds instead, accepting slightly lower ice-grip performance in exchange for year-round usability and reduced road wear.