You’ve most likely noticed tire numbers as someone who owns a car or drives a type of vehicle. And perhaps you’ve asked yourself, “What do the numbers on tires mean?” Here’s what you should know: The numbers on tires are as important as any part of your vehicle.
Understanding tire size numbers isn’t only for fact-knowing purposes, but it also benefits you in such a way that you’ll know how to care for your tires better and make smart decisions especially when replacing tires.
Why is it Important to Understand Tire Numbers?
Tires bear the full weight of the vehicle. They’re the only parts of your vehicle that come in contact with the road. Knowing how to read tire numbers will ensure that you choose the correct size.
Proper measurements maintain the overall performance of your car, while wrong measurements cause accidents. Everything that is engraved on the tire such as letters and numbers means something.
One must consider the width, strength, and thickness of the tire to be able to carry the vehicle and avoid any dangers while on the road. Being knowledgeable is also important as part of overall tire care.
What Do These Tire Numbers Mean?
Don’t worry, we have your tire numbers explained in detail below. Check them out:
Nearly the size of tires starts with one or more letters like P or LT. The letter informs the kind of vehicle the tire was originated for. First, P-Metric means Passenger vehicle tires. This is commonly seen on cars, minivans, light-duty pick-up trucks, SUVs, and crossovers.
There is also what we call Metric or Euro-Metric since this began in Europe, an equal kind of P-Metric size but with precise distinction in the load-carrying capacity. This can be noticed on European cars and some SUVs and vans. Another one is LT which means Light Truck like tow trailers and those that transport weighty cargo.
These two letters can either be located in the start or last part of the tire size. Examples of such are full-size vans, medium-duty, and heavy-duty pick-up trucks frequently on three-quarter or 1-ton trucks and SUVs.
Tires with ST that stand for Special Trailer. These are designated for trailers including fifth wheels and other travel trailers like boats. Lastly, tire size that ends with C or Commercial tires is commonly used for delivery like trucks and vans bringing heavy freight.
The first three numerics refer to the tire width. This measured in millimeters beginning from one side to the other side. For example, P235/55R15 is the tire size so 235 millimeters is the width of such a tire.
Following the width is the tire ratio or the height of the sidewall from the tire’s width. Some call it the percentage, the profile, or the measuring of the space between the edge of the rim to the top of the tire at the end of the border.
In the example given, P235/55R15, 55 is the aspect ratio, meaning — the height is like 55% that of the tire’s width. Note that the aspect ratio says much about how the vehicle can hold the tire. When the aspect ratio is large, so is the tire’s sidewall.
The letter R in the tire refers to the internal construction type. This means radial tires, the manufacturing quality of most tires these days. This kind gathers piles perpendicular to the direction of the travel permitting a trouble-free trip, lower rolling resistance for greater gasoline range, and tire’s longevity.
Some tires have D or Diagonal construction types often named conventional or cross-ply tires and can be found on motorcycles.
The last two digits after the construction type are what we call the wheel diameter. This is generally measured in inches. This is basically the size of your tire. Again, using the sample above, 15 means a 15-inch diameter wheel.
Tire Load Index
This is the entire load that a tire can drive when it is completely filled. The higher the load index means the more mass it can carry. A 65 load index can carry 639 pounds while a 123 tire load index can hold 3417 pounds. To know more about the load index of your car, you need to refer to a tire size chart.
Tire Speed Rating
Speed rating pertains to how fast the tire is made to go. This is known by a letter that matches the highest speed of the tire. For instance, the “S” rating means that the tire is allotted to go up 112 miles per hour.
Tire Identification number
This is a 12-digit descriptive number that indicates what factory producers make the tire as well as when (week and year) it was made. To distinguish how old the tire is, you may take a look at the last two numbers of the code.
Uniform Tire Quality Grading
The U.S. Department of Transportation comes about with a rating system to provide purchasers with facts to guide them in buying tires.
There is what we call Traction Grades which stipulates the wet traction of a tire under a managed tryout. Ratings are as follows: AA, A, B, C, and AA being the outstanding traction.
Temperature Grades relate to the resistance of heat. A tire with a higher temperature grade can maneuver at higher speeds. Tires graded “A” are highly resistant to heat generation. “B” is average, while “C” is the lowest.
This is a systematized government assessment to assist in seeing the wear rate of the tire. A grade of 300, fox example, would mean that it wears three times faster than a tire with a grade of 100.
Tire numbers are there for a reason and it is to help you choose the most suitable tires for your vehicle. Understanding the tire size numbers and how to read them correctly will substantially make a difference in your overall driving experience.
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