Tire Sidewall Graffiti: What Do the Numbers Mean?
Tire width The first 3 digits indicate the overall width of the tire in millimetres.
The symbol marked before the width in certain types indicates that it is a tire for a Passenger vehicle, sometimes denoted as P metric type loads.
The importance in this is that speed ratings ( see below ) change for P tires and non P tires.
Aspect Ratio Aspect ratio gives the relationship between the tire height and tire width.
In this particular example the tyre height is given as 60% of the overall tyre width.
In certain makes the "/" is replaced with an "X" Radial This indicates the tire type ( In this case R stands for Radial tires ).
Having radial tires will technically provide better fuel economy to your vehicle while also having a lesser bulging effect than bias ply tires ( which were the norm before radial tires were introduced ) *There is also the interesting fact that the steel wires in radial tires become magnetic with use and a significant alternating magnetic field is generated.
Wheel Diameter This will indicate the wheel diameter to which the tyre will fit ( In this example the tire fits a rim of 16 inch diameter ) Load Index The load index indicates the maximum load that a tire is certified to carry at maximum inflation pressure.
It is strongly recommended to buy a tire with an equal or higher load index than the vehicles' original tyres.
Depending on the load that you intend to carry in your vehicle you can decide the load index of the tires that would best suit your requirement by referring to the load index chart.
Speed Rating The speed rating gives an indication of the top speed at which the tire will operate.
This is an important factor that should be considered as tyres with a lower speed rating on a good car would definitely reduce its performance as well as generate the risk of an accident.
Mud & Snow The final letters provide additional information regarding the tire.
In the case of this example, the M and S indicate that the tire meets the required standard for a mud and snow tire.
This combination is sometimes expressed as, M+S, M/S and M&S.
Apart from M&S there are various other additional markings that can be found on different tires based on their uses.
Some such markings are, BSW: Black Sidewall WSW: White Sidewall OWL: Outline White Lettering TL: Tube Less TT: Tube Type ( tires must be used with an inner tube ) LL: Light Load SL: Standard Load XL: eXtra Load C: Commercial ( tyres for light trucks ) B: Bias belted ( tyres for motorcycles ) *Load Index and Speed Rating charts can be referred to here.
The symbol marked before the width in certain types indicates that it is a tire for a Passenger vehicle, sometimes denoted as P metric type loads.
The importance in this is that speed ratings ( see below ) change for P tires and non P tires.
Aspect Ratio Aspect ratio gives the relationship between the tire height and tire width.
In this particular example the tyre height is given as 60% of the overall tyre width.
In certain makes the "/" is replaced with an "X" Radial This indicates the tire type ( In this case R stands for Radial tires ).
Having radial tires will technically provide better fuel economy to your vehicle while also having a lesser bulging effect than bias ply tires ( which were the norm before radial tires were introduced ) *There is also the interesting fact that the steel wires in radial tires become magnetic with use and a significant alternating magnetic field is generated.
Wheel Diameter This will indicate the wheel diameter to which the tyre will fit ( In this example the tire fits a rim of 16 inch diameter ) Load Index The load index indicates the maximum load that a tire is certified to carry at maximum inflation pressure.
It is strongly recommended to buy a tire with an equal or higher load index than the vehicles' original tyres.
Depending on the load that you intend to carry in your vehicle you can decide the load index of the tires that would best suit your requirement by referring to the load index chart.
Speed Rating The speed rating gives an indication of the top speed at which the tire will operate.
This is an important factor that should be considered as tyres with a lower speed rating on a good car would definitely reduce its performance as well as generate the risk of an accident.
Mud & Snow The final letters provide additional information regarding the tire.
In the case of this example, the M and S indicate that the tire meets the required standard for a mud and snow tire.
This combination is sometimes expressed as, M+S, M/S and M&S.
Apart from M&S there are various other additional markings that can be found on different tires based on their uses.
Some such markings are, BSW: Black Sidewall WSW: White Sidewall OWL: Outline White Lettering TL: Tube Less TT: Tube Type ( tires must be used with an inner tube ) LL: Light Load SL: Standard Load XL: eXtra Load C: Commercial ( tyres for light trucks ) B: Bias belted ( tyres for motorcycles ) *Load Index and Speed Rating charts can be referred to here.
Source...