A 2006 survey in Britain showed that only 4% of consumers are aware that tires become more dangerous as they age. Most vehicle tires are often given a four-year validity period. This four-year expiration date begins from the day the tire was manufactured at the plant and not the date it was sold to a consumer or the date that it was installed on a vehicle. Thereafter, the tire may burst whilst in use.
The problem here is that most people have no idea what letters and numbers on their tire’s sidewall mean and they do not identify tire aging as a safety hazard.
The sidewall of the tire refers to the other surfaces of the tire that isn’t in contact with the road. This is the face of the tire you would see from the side view of a vehicle. The sidewall contains markings for the tire size, max pressure, expiry date, and brand.
Example: 205/55/R16 89V or P205/55/R16
P at the beginning tells us the tire type. It makes us understand that the tire is intended for passenger vehicles. If the letters “LT” were at the beginning, it would indicate that the tire was designed for a light truck, “T” indicates temporary or spare tire and no letters at the beginning indicate that the tire uses European metric.
205 tells us about the tire width. This is measured in millimeters from sidewall to sidewall. In this instance, the width is 205 millimeters.
55 gives us an idea of the tire height. It is the aspect ratio. This is the ratio of the tire’s cross-section to its width, expressed as a percentage. The 55 means that the height is equal to 55% of the tire’s width
R16 tells us about the wheel diameter. It specifies the size of the wheel rim the tire should fit into. In this instance, the tire will fit a 16-inch rim. Meanwhile, R stands for radial – layers of fabric whose cords run at right angles to the circumference of the tire. Some tires would have something like /ZR16. Z is the speed rating; it indicates the maximum speed at which a properly installed and inflated tire can be driven on. R for radial is the most common but we have B for bias belt and D for diagonal
89V is the Load index and speed rating 89 stands for the load index and V stands for the speed rating. The load index indicates the maximum load capacity of the tire; how much weight the tire can support if properly inflated. The speed rating could either be could be H, V, W or Y. Click here to view the Speed Rating Chart from Goodyear. Generally, ZR in the tire size would indicate a high-speed rating.
TIRE EXPIRY DATE
Elsewhere on the tire sidewall, you can find the manufacture or production date of the tire with this you can calculate its expiry date. You want to look for the DOT Symbol and the series of letters and numbers following the “DOT.” For tires manufactured from the year 2000 to present, the date of manufacture is the last four digits of the DOT code. The first two digits are the week of manufacture, and the last two digits are the year of manufacture. For our example 4202 would mean that the tire was manufactured in the 42nd week of 2002. This is important because a defective or expired tire could kill you.
DOT simply means the Department of Transportation and it indicates that the tire has passed all applicable Federal Motor Vehicle Safety Standards in the United States. The tire also contains thread wear indicator located where the thread meets the sidewall.
There are also other indicators like maximum inflation pressure number and The maximum load number. Written like this – MAX.PRESS 350 kPa (51 psi)