Asymmetric tyres carry two different tread patterns across their width, each doing a different job. The outer half is built for dry grip and stability through corners, while the inner half is designed to clear water and hold the road in the wet. To make sure each half ends up where it should, the sidewalls are marked Outside and Inside.
Two halves, two jobs
Look closely at an asymmetric tyre and the tread is clearly different from one side to the other. The outer shoulder typically has larger, more solid blocks for stability and grip when cornering and braking on dry roads. The inner shoulder has more open grooves to channel water away and resist aquaplaning. Combining the two lets a single tyre balance dry control and wet safety better than a uniform pattern can, which is why asymmetric designs are common on quality road tyres.
The Outside and Inside markings
Because the two halves are different, the tyre has to be fitted the right way up. The sidewalls are clearly marked:
- Outside (or "Side Facing Outwards") must face away from the car
- Inside must face in toward the vehicle
The simple check is to look at the sidewall facing out: it should read Outside. If the outward face reads Inside, the tyre is on the wrong way and the tread is doing the opposite of what was intended.
Why fitting direction matters
An asymmetric tyre fitted backwards puts the wet-weather inner pattern on the outside and the dry-grip outer pattern on the inside. The effect is reduced grip and stability in corners and weaker performance in the wet, the worst of both worlds. The tyre is not dangerous to fit in the sense of running backwards, as it is not directional, but it simply will not perform as designed.
More flexible than directional tyres
A useful advantage of asymmetric tyres is flexibility. Because they are not directional, they have no single rotation direction, they can be fitted on either side of the car and rotated freely, front to back or side to side, provided the Outside marking always ends up facing outward. This makes rotating them to even out wear much simpler than with a directional set, which can only move front to rear. The difference between the two designs is worth understanding when choosing tyres. Getting an asymmetric set mounted the right way round, with each Outside marking facing out, is part of a correct fitting, one of the details a fitter takes care of when a set ordered from a tyre site such as Tyres.co.uk is booked in at a local garage.
From the workshop: the Outside marking is the one to check, and it is the one that occasionally gets missed. A tyre fitted Inside-out will pass a glance and even drive fine in the dry, but it is quietly giving up grip in the corners and the wet where it matters most.
Common questions
What are asymmetric tyres?+
Asymmetric tyres have two different tread patterns across their width. The outer half is designed for dry grip and cornering stability, and the inner half for clearing water and gripping in the wet. The two work together to balance dry and wet performance.
What do Outside and Inside mean on a tyre?+
They mark which way an asymmetric tyre must face when fitted. The sidewall marked Outside must face outward, away from the car, and the side marked Inside must face inward. Fitting one the wrong way round reduces grip and handling.
Can asymmetric tyres be fitted on either side of the car?+
Yes. Unlike directional tyres, asymmetric tyres are not tied to a rotation direction, so they can go on either side and be rotated freely, as long as the Outside marking always faces outward.
How do I know if my tyres are fitted correctly?+
Check that the wording on the outward-facing sidewall reads Outside. If the side facing out says Inside, the tyre has been fitted the wrong way round and should be corrected, as it compromises both dry and wet performance.