I'm curious as to the rules with car tints on the driver and passenger side front windows. I'm fairly certain only a low level is allowed for them (35 per cent VLT) but I often see cars with driver/passenger side front windows that seem to be almost completely tinted. Isn't this checked during the WoF process? Or perhaps it's me and I just don't realise how dark a window is with a 35 per cent VLT rating? Daniel Elder, Auckland

VLT means "visible light transmittance" and is the amount of "visible" light that passes through a windscreen and windows. A clear windscreen has a VLT of about 85 per cent, although the VLT can be as low as 70 per cent. If an overlay is applied to a window, the overall VLT is measured as the amount of light passing through the glass and the overlay. This means that if a tinted film overlay of 35 per cent VLT is applied to a front side window that already has 70 per cent VLT, the overall VLT will be well below 35 per cent.

No tinted overlays are permitted on the windscreen. You may have anti-glare bands that extend no lower than the bottom of the sun visors when folded against the windscreen.

The overall VLT is checked by using a calibrated VLT meter. Most vehicle testing stations have a VLT meter so you should see them or a reputable window film installer if you would like to have the VLT of your tinted windows measured. VLT meters may be used during WoF checks if it is suspected that the VLT is outside the permitted range.


Note that VLT measurements are only relevant to transparent overlays. VLT is not an appropriate measurement for non-transparent overlays, such as printed or perforated advertising film.

There are restrictions on overlays because they can reduce the driver's ability to clearly see the road, other road users and potential obstructions.

At the Waterview onramp heading west there is a truck and T2 lane. Is this lane only to be used in peak hours? There are no time-limit signs. It is frustrating to be in a long queue wasting fuel when there is no one in the T2 lane out of these hours.
Peter Broadhurst, Pt Chevalier.

If there are no time limits posted on this lane, then it is permanently reserved for trucks and vehicles with two or more occupants. As a general rule, truck lanes do not have specified hours, but are for these vehicles 24 hours a day.