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Tyres of different sizes, different states of wear, or a size other than the vehicle's specification, so the wheels turn at speeds the module did not expect. It is not a fault in any component, which is why it is worth naming: everything tests correctly and the codes name sensors, stability systems and the transmission.

Small differences matter more than people expect. Traction and stability systems compare wheel speeds continuously and detect slip from differences of a fraction of a percent, so a few millimetres of tread difference across an axle reads as permanent low-level slip. On a four-wheel-drive vehicle it is mechanically damaging as well — mismatched rolling radii front to rear force a centre differential or coupling to absorb a difference that never ends, which overheats and wears it.

The commonest routes are a single replacement tyre and a space-saver spare left on. One new tyre against three half-worn ones is enough. Measure rolling circumference rather than comparing sidewall markings, since two tyres of the same nominal size from different manufacturers differ, and check the pressures first — a significantly underinflated tyre produces the same effect with correct tyres fitted.