Information on Tyres
Each small prints on the tyres mean something that can be usefull to you while selecting a tyre for your car.Lets say for example the information on sidewalls are gives as.
P235/75 R15
Treadwear 480
Traction AA
Temperature A
M&S
105S
and ofcourse the manufacturer's name and tyre name.Let us find out wat all this information mean
(1)Tyre Type.
The letter P in the pic designates that it is a passenger vehicle.Similarly other designations are LT for light truck,T for temperory tyre or spare tyre.
(2)Tyre Width.
The 235 is the width of the tyre measured in (mm) from sidewall to sidewall.
(3)Aspect Ratio.
This no tells the height of the tyre.It is described as percentage of the tyre width.In our example the aspect ratio is 75.So the height of the tyre is 75% of the width,
(75x235=176.25mm)
Smaller the aspect ratio the wider the tyre in relation to height.High performance tyres used in F1 racing have small aspect ratio cos these tyres provied very good traction and stability.
(4)Rim Diameter.
In our example the letters R15 gives the size of the rim n tyre details.Like R is for radial and 15 is the diameter size of rim in inches.
(5)Tread Wear.
The higher the number the longer you can expect the tread to last.Tyres with higher treadwear no last longer then the tyres with smaller no.
(6)Traction.
The tyre Traction is AA,A,B,or c with AA at the top of the list.This rating is based on the tyres ability to stop the car on wet and concrete surfaces.
(7)Temperature.
The tyre tempertaure ratings are A,B and C.This rating is a measure of how well the tyres can dissipate heat and how well it handles the build up heat.The temperature grading is done to a properly inflated tyres without any overloads.As the load increases the build of heat in tyre all increases.
(8)M&S.
The letters M&S stand for Mud and Snow.It means that the tyre can be used in both muddy and snowy region.
(9)Service description.
The letter 105S stands for Load rating and Speed rating.105 is the Load rating of the tyre ie the tyre has a maximum load rating of 105 which corresponds to a load capacity of (924.87kg).The different Load ratings have a standared table of the no and the weight in kg's.
The no followed after load rating give the maximun speed the tyre can handle.Here 5 corresponds to 180 kmph.
(10)Calculating the Tyre Diameter.
Now that we know what the numbers mean we can calculate the tyre diameter.We know the height of the tyre is given by the aspect ratio
235x75=176.25mm(6.94inches)
Then we add twice the tyre height of the rim diameter,
2x6.94 + 15= 28.9 inches
This is the Tyre diameter.
Information by Saurabh.Shah
