Ever thought of all the markings that you see on the sidewall of a tyre? Ever wondered they might give you some important information that you could use? CarToq helps you with 5 important markings to check while buying a new tyre.
The sidewalls of a tyre are filled with a lot of information that one can use but more often than not, we tend to ignore them as most are unaware of what they mean. The most common marking that one may look into, is the size of the tyre which has been discussed in: Tyres: All that you have to know about upsizing There are other markings indicating maximum tyre pressure, load, rotation etc. We shall look at a few of them
Date of Manufacturing
Old tyres should never be used as the rubber on them degrades irrespective of the fact if they are used or not. Tyres more than 6 years old should not be used. It is unlikely that a dealer would store tyres that old. But a year old tyre may have been lying in a corner of the dealer’s storage space in stagnant water or rats biting off bits. This is not a tyre that you should use.
On the sidewall of the tyre, a set of 4 digits are engraved/stamped to indicate the manufacturing date. These digits are usually small sized and will be in a box.
Image Courtesy: oponeo.co.uk
Here 4208 mean that this tyre was manufactured in the forty-second week (42) of 2008 (08). The format is standard for all manufacturers.
So ensure that the tyre you buy is not too old.
Some tyres are designed to function only in a particular direction of rotation. These are known as unidirectional tyres.
Image Courtesy: classicmotorcycles.com
This mark indicates the direction of rotation and thus one should ensure it is not installed in the opposite direction which may hamper its functioning.
Maximum Tyre Pressure
Tyres also indicate the maximum air pressure it can handle. This is indicated as “42 psi” or similar. Air pressure is measured in pounds per square inch and is denoted as “Psi.” This is the same unit displayed at air pumps in the filling station. Your vehicle’s manufacturer will recommend tyre pressures and one should stick to that but do keep this figure in mind to avoid over inflation of the tyre.
Here you can see that max recommended pressure is 52psi.
A tyre is also designed to handle a maximum amount of weight it can bear. Your car’s weight is divided amongst four tyres.
For example, if your car weighs 2 tons i.e. 2000Kgs, every tyre should be able to support 500Kgs of load. If it can’t then there is a risk of tyre failure, which may lead to a fatal accident.
The load index of a tyre will be mentioned after the size of the tyre, like it is in this picture.
Image Courtesy: JK Tyres
The numerals 82 refer to the load index which means that this tyre should support a max weight of 475Kgs. The following table should help you decipher common load indices. This table is vast hence we have only included indices for cars weighing 1 ton = 1,000Kgs to 4 tons = 4,000Kgs.
[table id=1006 /]
Normally, the load bearing per tyre of your car is more than one can ever use. However, it is best to have a tyre which can support more weight rather than something which may fail with all the seats full.
This is the corresponding letter against the load index. This letter denotes the maximum speed that the tyre can sustain for 10 minutes without breaking apart. These speeds maybe achievable for a few cars but sustaining them may not be possible on public roads.
Speed rating is ‘T’ in this pic which mean that this tyre is good for max speeds of up to 190kmph.
Here is a table decoding the ratings:
[table id=1007 /]
A tyre specific to your car will have speed ratings which may not practically be achievable by your vehicle; however it is important for you to know if you do intend to modify your car for higher speeds.
So the next time you are buying tyres, these checks will definitely help you choose the right tyre for your car.