Cross-ply tyre
The classic tyre construction in which the carcass plies run diagonally across each other. Standard until the 1960s – and the period-correct fitment for many classic cars.
In a cross-ply tyre (US: bias-ply) the fabric plies of the carcass run diagonally at an angle of roughly 30 to 40 degrees to the direction of travel, crossing from ply to ply. This construction was the worldwide standard from the dawn of the motor car until the 1960s – practically every pre-war car and many post-war classics left the factory on cross-plies.
Dynamically the cross-ply differs markedly from the more modern radial tyre: the sidewalls are stiffly connected to the tread, the contact patch is narrower and rounds off under load. The result is the typical, slightly floating steering feel, less cornering grip and a tendency to follow ruts and road joints. In return, the tall, narrow silhouette matches the historic appearance exactly; the classic size marking is in inches, for example 5.60-15.
For classics this poses the basic question of originality versus driveability: those who want to appear period-correct – at concours events or strictly historic rallies – run cross-plies; for regular road use many convert to radials. When converting: never mix constructions on the same axle, observe the car's approvals and allow for changes in handling and speedometer reading.
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Related terms
Regularity rally
Classic-car motorsport where precision counts, not speed: hold prescribed average speeds and target times as exactly as possible.
Pre-war vehicle
Vehicle from the era before the Second World War, usually up to the 1939 model year. The term is not officially defined; the cut-off varies by source.
07er-Kennzeichen
Germany's red classic-car plate (rotes 07-Kennzeichen): one transferable plate for several historic vehicles, usable only for events plus test, transfer and workshop drives – never for everyday use.