Current tread depth legislation requires that truck tyres must have a minimum of 1mm of tread in a continuous band throughout the central three-quarters of the tread width and over the whole circumference of the tyre. The same regulation applies to regrooved tyres. The driver of the vehicle is responsible for making sure his/her tyres are legal and in a roadworthy condition. The penalty for driving with an illegal tyre is 2,500 and three penalty points per tyre.

When driving in wet weather, the tread pattern of the tyre helps to evacuate surface water from the road. As the tread begins to wear down, the tyre gradually loses the ability to evacuate all the water from the road surface, which increases stopping distances in the wet. The lower the tread depth, the greater the risk of aquaplaning.

Incorrect wheel alignment may cause the tyres to scrub against the road surface to a greater degree, increasing wear and rolling resistance. If any of the wheels of a 12-wheel tractor and trailer are not properly aligned, the total drag on the vehicle increases. Misalignment may also cause greater aerodynamic drag when the tractor and trailer are not tracking parallel to the direction of travel.

Any tyre regrooving should take place at around 4mm of remaining tread. After regrooving, the 1mm law still applies. It is also law that the tyre is regrooved in the pattern designated by the tyre manufacturer failure to observe this will render the tyre illegal. If any of the tyres cords are exposed during regrooving, the tyre should be disposed of. [N.B. It is important to consider that budget tyres might not be designed with enough extra rubber to regroove tyres.