The legal minimum tyre tread depth for a car in Ireland is 1.6mm across the central three-quarters of the tread around the full circumference. The RSA recommends replacing tyres before they reach that limit: its guidance recommends at least 3mm for safety. Legal and prudent are different thresholds, especially on wet roads where the remaining tread has to move water away from the contact patch.
The difference is measurable. A tyre at 2.5mm may still be above the legal minimum, but it is below the RSA’s recommended 3mm. Waiting until 1.6mm may save some tread life, but it leaves less margin and can make a long wet journey a poor time to discover uneven wear. Check all four tyres, not only the front pair; rear tyres may wear more slowly but still age, crack or become damaged.
In October 2025, the RSA reported that 182,160 motorists, or 10.5%, failed the NCT due to tyre condition over the preceding 12 months. It also recorded 43,184 vehicles with dangerously low tread below 1.6mm. This is why a quick visual check is useful before booking an NCT or setting off on a motorway trip.
Look for cuts, bulges, exposed cords and uneven shoulders as well as tread depth. A coin can be a rough screening aid, but a tread-depth gauge gives a clearer millimetre reading. Check pressure against the vehicle placard or handbook; the pressure printed on the tyre is usually a maximum, not the car’s recommended setting. For a used-car inspection, include tyre age and matching sizes in the negotiation, not just the advertised NCT date.
