What’s your tire telling you?
Friday, December 16th, 2011
When it comes to tires, most of us glance at them – to make sure they’re not flat – before jumping in the car and heading to our destination. We rarely think of tire codes as information that anyone beyond an automotive or tire technician or store manager would need to know. Believe it or not, these codes can tell you a lot about your tires and how to take better care of your vehicle.
Tire size and type
Tire type (P) Tire type defines the proper use of the tire. For example, the “P” on the tire shown here means that this is a passenger car tire. If the tire had an “LT” designation, the tire would be for a light truck.
Tire width (215) The number beside the tire type is the width of the tire measured in millimetres from sidewall to sidewall. This tire width is 215 millimetres.
Aspect ratio (65) Aspect Ratio is the ratio of the height of the tire’s sidewall to its width represented as a percent. In our example, 65 means the height is equal to 65% of the tire’s width.
Tires with a lower aspect ratio take less time to transfer energy from the steering mechanisms to the wheels and tread. So a lower aspect ratio makes the car react faster to your controls. Aspect ratio also affects tread. The lower the ratio, the wider the tread contacting the ground and the better traction (grip) you’ll have when turning.
Construction (R) Construction tells you how the layers of the tire were put together. The “R” stands for Radial, which means the layers run radially across the tire. A “B” stands for bias construction, which means the layers run diagonally.
Most passenger and light truck vehicles will have an R rating. Radials deliver longer tread life, less fuel consumption, improved ride and better handling on the road.
Diameter of wheel in inches (15)
Indicates the wheel diameter in inches. The diameter of this wheel is 15 inches.
Speed rating (H)
A tire receives its speed rating by meeting minimum government standards for reaching and sustaining a specified speed. What does that mean to you? Well, in general, a higher speed rating will result in better car handling.
Two important notes when considering speed rating:
- We do not recommend downgrading the speed rating of your tires. This may result in poor handling and unpredictable steering. However, if you want better cornering response, there is no problem installing a higher speed rated tire on your vehicle. Please connect with one of our tire experts for help finding your best fit.
- Never mix and match tires with different speed ratings on your vehicle; this will cause serious problems with the handling of your vehicle.
Tire construction
POLYESTER/STEEL
Thought your tires were only made out of rubber? Think again. Modern tires use a combination of materials. The foundation of the tire is the plies (layers of nylon, polyester, fibreglass or steel) just beneath the tread that provides flexibility and strength.
Radial tires now rule the road and are constructed with steel or fabric carcass plies crossing the tread at approximately a 90° angle, and two or more belts circle the tire under the tread. The sidewalls flex while the tread remains rigid, accounting for the characteristic sidewall bulge of a radial. The tread runs flatter on the road with a better grip and superior handling and mileage.
Maximum cold inflation and maximum tire pressure
MAXIMUM PRESSURE 44 PSI
This indicates the maximum operating inflation pressure of the tire. It does not indicate the manufacturer’s recommended inflation pressure, nor does it indicate the proper air pressure based on the vehicle the tire is
mounted on.
Download the complete tire guide here.
