For common non-winter road tyres with moulded tread-wear indicators in New Zealand, the legal minimum tread depth is 1.5 mm in the principal grooves that contain those indicators, around the whole circumference. Correct pressure is the figure specified for your vehicle, usually found on the driver's door frame or in the handbook.
Those are minimum and vehicle-specific requirements, not a promise that every tyre is safe until one number is reached. Check tread, pressure and visible condition regularly. If wear is uneven, damage is visible or pressure keeps dropping, arrange a proper inspection.
What is the legal tyre tread minimum in New Zealand?
NZTA's current guidance states that a tyre with moulded tread-depth indicators needs at least 1.5 mm of tread in every principal groove that contains those indicators, around the whole circumference. A principal groove is one of the wider grooves that contains a moulded tread-wear indicator.
Many tyres mark the location of these indicators with a small triangle or the letters TWI on the sidewall. The raised indicator in the groove helps show how far the tread has worn, but a proper tread-depth gauge gives a clearer measurement.
This guide describes common non-winter passenger tyres. Winter tyres have a different minimum, and the small number of tyres without moulded indicators are measured differently. If either case applies, use the current NZTA inspection guidance or ask a tyre professional rather than applying the common 1.5 mm method by assumption.
How to check tyre tread without guessing
Do not rely on a single measurement or a casual look from the side. If you cannot identify the correct grooves, or the reading is close to the minimum, ask a tyre workshop to check it.
- Park safely on a level surface and turn the steering only if needed to see the front tread.
- Find the principal grooves that contain the moulded indicators.
- Measure at several positions around each tyre, because one area may be more worn than another.
- Check all tyres, not only the easiest one to reach.
Where to find the correct tyre pressure
Use the pressure recommended by the vehicle manufacturer. NZTA says this can usually be found on the inside of the driver's door or in the vehicle handbook. Front and rear tyres may have different figures, and the recommended figure can change with load.
Check pressure while the tyres are cold. NZTA suggests checking about monthly, as well as before a long journey. A dashboard tyre-pressure warning is useful when fitted, but it does not replace looking at the tyres and checking with a gauge.
Visible damage matters as much as the numbers
Tread depth and pressure are only part of a tyre check. Look for cracks, bubbles, cuts, sharp objects and any cord or internal material showing through. A tyre can have measurable tread and still need immediate professional attention because of damage.
Repeated pressure loss also needs investigation. Adding air may restore the reading temporarily, but it does not identify a puncture, valve problem or rim leak.
How tyres relate to the WoF
Tyre condition, including tread depth, is part of a WoF inspection. The check is made on the day of inspection. NZTA reminds owners that tyres can reach the minimum after a pass, so waiting for the next WoF is not a maintenance plan.
If you are preparing for a WoF, check all four tyres beforehand. If a tyre is damaged, near the minimum or losing air, deal with that concern before relying on the inspection date.
Official sources
The legal and safety details were checked against NZTA pages on 2 August 2026. The Vehicle Inspection Portal says its technical guidance was current on 31 July 2026 and may be superseded.