"P" means this is a passenger car tire (as opposed to a tire made for a truck or other vehicle). P-metric is the U.S. version of a metric tire-sizing system.
"225". Section Width: The width of the tire in millimeters from sidewall to sidewall. This measurement varies depending on the width of the rim to which the tire is fitted: larger on a wider rim, smaller on a narrow rim. The number on the side of tire indicates the width, measured with the tire fitted to the recommended, or design, rim width.
"60" Aspect Ratio: The ratio of height to width; this tire's sidewall height is 60% of its width.
"R" Construction: How the plies are constructed in the tire carcass. "R" means radial. "B" in place of the "R" means the tire is belted bias construction. "D" in place of the "R" means diagonal (or bias) construction.
"16" Rim Diameter: The diameter of the wheel (or rim) in inches.
"98" Load Index: Load Index is a rating which reflects the load capacity of the tire. This tire has a load capacity of 1,653 lbs. For a more complete listing see the chart under Load Index and Speed Rating.
"V" Speed Rating: This tire has an industry-standard maximum service speed of 149 mph. Tires using an older European system carry the speed rating in the size description: 225/60VR16. Different letters correspond to different maximum service speeds.
Four sizing systems exists for passenger tires today, but we'll explain the two most commonly used:
Examples: P215/65SR15, P215/65R15, P215/65R15 95S
P = Passenger Car Tire
215 = Section Width in Millimeters
65 = Aspect Ratio
R = Radial Construction
15= Rim Diameter in Inches
95 S = Service Description (Load index and Speed Rating)
The aspect ratio is assumed to be 82 if not present in identification number.
Examples: 155SR13, 155R13, 155R13 78S
155 = Section Width in Millimeters
S = Speed Rating
R = Radial Construction
13 = Rim Diameter in Inches
78 S = Service Description (Load index and Speed Rating)
With the aspect ratio included:
Example: 185/70SR14, 185/70R14, 185/70R14 88S
185 = Section Width in Millimeters
70 = Aspect Ratio
S = Speed Rating
R = Radial Construction
14 = Rim Diameter in Inches
88 S = Service Description
The speed rating is the maximum service speed of a passenger car tire. Light truck (LT type) tires may not be speed rated. Here is a list of rating indicators and their mile-per-hour equivalents. This rating system applies to all tire makers.
Rating / Maximum Speed
Q - 99 mph
S - 112 mph
T - 118 mph
U - 124 mph
H - 130 mph
V - Above 130 mph
V - 149 mph
Z - Above 149 mph
When "ZR" appears in the size designation with the service description, the maximum speed is as indicated by the service description.
Tire Designation / Max. Speed
P275/40ZR17 93W - 270 km/h (168 mph)
P275/40ZR17 93Y - 300 km/h (186 mph)
For tires having a maximum speed capability above 240 km/h (149 mph), a "ZR" may appear in the size designation. For tires having a maximum speed capability above 300 km/h (186 mph), a "ZR" must appear in the size designation. Consult the tire manufacturer for maximum speed when there is no service description.
Speed Symbol / Speed (mph)
V* - Above 130
V - 149
Z** - Above 149
W - 168
Y - 186
• For unlimited V Tires without Service Description, the speed category is over 130 mph.
** For unlimited Z Tires without Service Description, the speed category is over 149 mph.
Tires are highly engineered products designed to support the weight (load) of the vehicle, its passengers, and its contents. In addition the tires have the responsibility to make the car accelerate, decelerate (or stop), and corner under a wide variety of weather and road conditions. They must do this under normal conditions and in evasive maneuvers. We as drivers and passengers also ask the tires to carry us in quiet comfort and security and provide a reasonable tread life.
As Sumitomo Tires increase the tire's performance capability, moving up through the speed ratings from non-rated passenger tires to the highest of the Z-Rated tires, the prices of tires usually follow suit. However, one of the best values today is a tire designed, engineered, and produced for your vehicle and the way you drive. While the price for the most of life's necessities have increased over the years, tire prices have continued to be quite reasonable.
Sumitomo Tires do not recommend downgrading the speed ratings of tires for your vehicle. Speed Ratings are a durability standard defining a tire's ability to withstand, or control, heat and growth. The components engineered to do this add performance characteristics and benefits to the tire commiserate with each speed rating level. This is not to say that all tires of equal speed rating are equal in all respects. However, within a tire manufacturer's line of products an H-Rated tire usually handles, or "performs" better than an S-Rated tire, and a Z-Rated tire usually handles better (has crisper steering response and overall greater cornering grip) than an H-Rated tire. Each tire line (or model) within a speed rating can be designed and engineered to provide specific performance characteristics depending upon the typical user's wants, needs, and desires.
You should try to match the tire's handling personality to that of your car. Your car is probably one of the most expensive purchases you have made. Ensure that you maintain the performance characteristics you like about the vehicle by selecting a tire with equal or greater performance capabilities.
Uniform Tire Quality Grading System or UTQG, is the standard by which tire manufacturers rate the quality of their tires. With the exception of snow tires, the DOT requires the manufacturers to grade passenger car tires based on three performance factors: treadwear, traction, and temperature resistance.
The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track.
A tire graded 200 would wear twice as long on the government test track as one graded 100. Your actual tire mileage depends upon the conditions of their use and may vary due to driving habits, service practices, differences in road characteristics and climate. Note: Treadwear grades are valid only for comparisons within a manufacturer's product line. They are not valid for comparisons between manufacturers.
Traction grades represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. The Traction grade is based upon "straight ahead" braking tests; it does not indicate cornering ability.
The temperature grades represent the tire's resistance to the generation of heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperatures can cause the materials of the tire to degenerate and thus reduce tire life. Excessive temperatures can lead to tire failure. Federal law requires that all tires meet at least the minimal requirements of Grade C.
Temperature grades are representative of a properly inflated and not overloaded tire. Excessive load, or underinflation, or excessive speed can increase heat and lead to premature failure.