What are colours dots and lines on tyres for?
A new tyre carries a lot of information, including coded one. Not all drivers know what colours lines and dots on a tyre tread and sidewall mean, and whether it is worth to know?
Let's start with colours lines around the circumference of a tyre tread. The Colours of these stripes and their location are a manufacturer's choice. They are particular for each tyre size and model and applied to an extruded rubber band, which becomes a tread at the last stage of production. Since tread compound and tread itself influence basic characteristics of a tyre model, the markings are applied to a tread running surface. These colours lines are visible when you cannot see sidewall markings. These markings are especially important for people at tyre factories and for logistics specialists in large warehouses.
Colour marks on tyre sidewalls are not so noticeable to customers, but they carry important information about characteristics of a particular tyre. These are dots (less often triangles) of a certain colour, which are applied at a tyre factory after each tyre is tested.
The yellow dot (triangle) indicates the lightest part of the tyre circumference. It is an important indicator for tyre mounting to a rim, in order to align it with the heaviest point on a rim, and avoid the use of heavy weights when balancing an assembled wheel. It is necessary to know that either the valve stem or the point diametrically opposite to the L symbol on the disk is considered the heaviest point on a disk (it is not always applied). Some manufacturers put a colour dot instead of the L symbol, or do not mark the lightest place on the disc at all.
The red dot (triangle) marks the heaviest spot on the tyre circumference. More precisely, this is the place with the largest tyre radius. If you measure a tyre with an accuracy of a fraction of a millimetre, there will be a segment with a slightly increased radius. Some manufacturers refer to it as the maximum point of radial force variation (RFV). Here, in the tyre body, the edges of the carcass strips are joined, therefore the stiffness and weight of a tyre are higher in this place. If a point of the smallest diameter is indicated on the rim, then, during installation, it is aligned with the red dot on the tyre. But in tyre shops such a scrupulous approach is rarely practised, therefore if there is an L mark on the disc, the red dot of the tyre is aligned with it, which is quite acceptable.
Not all tyres have a white dot (circle, triangle) on the sidewall. In its meaning, this point is opposite to the red point, that is, this is the place with the minimum radial force variation (RFV), the softest part of the tyre. Ideally, it should be aligned with the point of the largest disc radius or with a point diametrically opposite the L mark on the disc. In practice, this is only done in automotive factories when a new tyre is mounted on a new rim.
So, for an average driver, the colour marks on the tyres are not important. This information is rather for those who carry out vehicle service (maintenance). However, there are situations when specialists cannot be trusted, and if you are used to controlling everything what is done with your car, we recommend that you understand the meaning of colour markings.