OUTSIDE / INSIDE (asymmetric tyres)
The tyre is asymmetric: its inner and outer tread halves do different jobs, so the sidewall marked OUTSIDE must face out, away from the car.
What to do with it
Mount it with OUTSIDE visible when the wheel is on the car. If the tyre also has a rotation arrow, it is both asymmetric and directional: follow the arrow too.
- What it looks like
- The word OUTSIDE on one sidewall and INSIDE on the other, on tyres whose tread looks different on its two halves.
- Set by
- UN Regulation No. 30, paragraph 3.1; 49 CFR 571.139, S5.5.1(b)
In detail
- Continental: the inner tread of an asymmetric tyre handles water and aquaplaning; the outer has rigid blocks for cornering grip on dry roads.
- Michelin: “one sidewall of this type of tyre is marked ‘Outside’.”
- The regulations follow it: UN R30 requires the markings on both sidewalls of a symmetrical tyre but “at least on the outer side wall in the case of asymmetrical tyres”, so the size and approval marks may be on the OUTSIDE face only. In the US the full date code goes on the intended outboard sidewall.
What it does not mean
OUTSIDE does not mean the tyre is for the left or right of the car, and INSIDE is not a defect or a second-quality side.
Markings that go with it
Sources
Each document was fetched and read on the date shown; the clause is the one that sets this marking.
- Michelin (UK): Tyre rotation: extend the life of your tyres — “Asymmetric, Symmetrical and Directional tread patterns”: “This is indicated on the outer sidewall of the tyre by an arrow and one sidewall of this type of tyre is marked ‘Outside’.” Checked 2026-09-28.
- Continental (UK): Tyre tread patterns and depth — “Asymmetric tread pattern”: “A tire with an asymmetric pattern features two separate tread designs, one on the inner half and another on the outer half of the tire.” Checked 2026-09-28.
- UNECE, as published in the Official Journal of the EU: UN Regulation No. 30 — Uniform provisions concerning the approval of pneumatic tyres for motor vehicles and their trailers, Revision 3 (OJ L 201, 30.7.2008) — paragraph 3.1: Tyres bear the markings “on both side walls in the case of symmetrical tyres and at least on the outer side wall in the case of asymmetrical tyres”. Checked 2026-09-28.
- US National Highway Traffic Safety Administration, on eCFR: 49 CFR 571.139 — Standard No. 139, New pneumatic radial tires for light vehicles — S5.5.1(b): The TIN goes “on the intended outboard sidewall of the tire”. Checked 2026-09-28.