In most European countries the legal minimum tread depth requirement for passenger cars is 1.6 mm. As an indication to the consumer, there are tread wear indicator bars in the main grooves of the tyre that become level with the tread surface at approximately 1.6 mm of remaining tread.
In addition to acknowledging the above, we recommend that all passenger and light truck tyres in highway motor vehicle application be removed from service at the following tread depths:
• summer / high performance tyres, all season tyres = 3 mm
• winter tyres = 4 mm
These recommendations are based upon our testing as well as real world experience which shows that drivers can maintain the performance potential (e.g. wet grip) of their tyres by replacing them before they reach the regulatory minimum tread depth of 1.6 mm. This applies especially to winter tyres for which winter driving properties such as snow traction are significantly reduced at tread depths below 4 mm.
Once tyres are applied to a vehicle and put into service, they are considered “used”. There are risks associated with the purchase of used tyres for which the service history is uncertain or unknown. Used tyres may have been exposed to improper service and may have damage that could eventually lead to a tyre disablement.
Not all tyre damage or conditions that can lead to a tyre disablement are easily detectable. For instance, improper repairs or damage to a tyre’s inner liner can only be observed through an inspection of the inside of the tyre, demounted from the wheel. A qualified tyre service professional should inspect the internal and external condition of a used tyre prior to application. If a used vehicle is purchased and the history of the tyres is unknown, it is recommended that the tyres be inspected by a tyre service professional, including demounting for internal inspection as appropriate for the characteristics as recommended below.
DO NOT purchase, sell, or install used tyres that exhibit any of the following characteristics:
• Any punctures, or other penetrations, whether repaired or not.
• Indication of internal separation, such as tread or belt separation (e.g.,bulges, bumps, lumps, localised tread wear, vibrations, unusual tyre noise, etc.)
• Indication of run-flat, under inflated, and/or overloaded damage (e.g. inner liner abrasion, delamination, or discolouration; excessive tread shoulder wear, etc.)
• ANY inner liner or bead damage.
• ANY history of continuous inflation pressure loss requiring frequent re-inflation.
• Defaced or removed DOT tyre identification number (TIN), which is located on the tyre sidewall.
• Tyres that have a date code that is older than 10 years. The date code – the last three or four digits of the DOT TIN – indicates the week and year the tyre was manufactured. Vehicle manufacturers may recommend a different chronological age at which a tyre should be replaced based on their understanding of the specific vehicle application; Continental Tyre recommends that any such instruction be followed.
• Involved in a recall or a replacement programme.
• Inadequate tread depth for continued service (i.e. nearly worn out). Tyres with a tread depth of 2/32” or less at any point on the tyre are worn out.
• Chemical, fire, excessive heat damage, or other environmental damage.
• Designated as a “scrap tyre” or otherwise not intended for continued highway service.
• Prior use of tyre sealant or balance/filler material.
• Tyres that have been altered to look like new tyres (e.g., a re-grooved tread).
• Labelled on the sidewall as “Not For Highway Use”, “NHS”, “For Racing Purposes Only”, “Agricultural Use Only”, “SL” (service limited agricultural tyre), or any other indication that the tyre is barred from use on public roads.