What Does the Inner Liner Do?

The inner liner is a layer of specially formulated rubber on the inside of a tubeless tyre. Its job is to reduce the rate at which air can pass through the tyre structure and help maintain inflation pressure.

Unlike older tyre designs that used a separate inner tube, most modern car tyres rely on the tyre’s inner liner, the bead and the wheel rim to form an airtight system.

Why Can a Tubeless Tyre Still Lose Pressure?

A sound inner liner does not mean a tyre will never lose air. Pressure can still escape through a puncture, a damaged bead, corrosion or damage on the wheel rim, a leaking valve, or damage to the tyre itself.

Tyre pressures also change with temperature, which is why pressures should still be checked regularly even when there is no obvious puncture.

What Happens if the Inner Liner Is Damaged?

Damage to the inner liner can affect the tyre’s ability to retain air and may make a repair unsuitable. Any tyre that has been driven significantly underinflated or flat should be inspected internally because heat and flexing can cause damage that is not visible from the outside.

Inner Liner and Puncture Repairs

A professional puncture inspection normally involves removing the tyre from the wheel so the inside of the tyre can be checked. The location and type of damage, together with the condition of the inner liner and tyre structure, determines whether a repair is appropriate.

For more information, see our puncture repair guide and tyre pressure guide.