See You Again Truck and Tire
How To Determine Tire Size
Once yous take determined it's fourth dimension to buy tires, you'll need to know what size tires are correct for your vehicle. This information is usually inside your car'south doorjamb, in your possessor'south transmission. To ensure your current tire or a replacement tire you may be looking at matches your vehicle's requirements, it will be adept for your to sympathise how tire sizing works. Yous may take never paid attention to the cord of numbers and letters on every tire, merely it's a gilded mine of information.
If you lot're unsure of how to read tire measurements from your tire walls, the information and graphics below volition tell you lot how to read tire size, understand and interpret it. If you decide you lot desire to substitute a new size or tire blazon, consult an authorized tire retailer who tin expertly advise yous, because many optional tire sizes may have different load capacities and could crave wheels of a different rim width or diameter and different inflation pressure.
Metric Sizing
Most rider cars, SUVs and light pickups (1/2 ton and smaller) will come with tires that are either P-Metric or Euro-Metric. For P-Metric tires, you'll meet the letter "P" before the number sequence begins: P225/70R16 97H. P-metric is a designation standardized by the Tire and Rim Association for a "passenger machine" tire type. For Euro-Metric there will exist no preceding letter before the number sequence begins: 225/70R16 98H. Euro-Metric is a designation standardized by the European Tyre and Rim Technical Organisation for a "passenger auto" tire type. Both P-Metric and Euro-Metric size tires are designed to primarily be used on passenger vehicles, which can include cars, minivans, SUVs, and other low-cal duty pickup trucks.
If your vehicle is an SUV, Pickup truck or van, you might run into a different type of size designation on your placard that is specific for heavy duty calorie-free trucks and vans, especially common on ¾ ton and larger pickup trucks and vans. At that place are two mutual size types in this category, LT-Metric and Euro-Metric Commercial (aka C-type). Both size types are metric and so use the same structure as P-Metric and Euro-Metric but have some unlike characters in the size that differentiate them from their passenger car cousins. LT-Metric tires will have the letters "LT" before the size number sequence: LT245/75R17 119/116R Load Range Eastward. Notice that there are ii load index numbers and a Load Range, see the section on Load Alphabetize for more info. LT-Metric is a designation standardized past the Tire and Rim Association for a "light truck" type tire. Euro-Metric Commercial or C-Type tires will look very similar to a rider Euro-Metric size except that there will be a "C" right later the rim size: 23/65R16C 121/119R. Detect that the C-type tires also take two load index numbers. Euro-Metric Commercial, or C-Type is a designation standardized by the European Tyre and Rim Technical Organization for a light truck type tire. Light truck tires are designed to be used on vehicles capable of carrying heavy cargo and are commonly simply specified past a vehicle manufacturer on vehicles exceeding a certain load chapters.
Other types of tires that autumn into the Metric sizing blazon are Temporary Spares, they start with "T". If y'all come across a size that starts with "ST," that means "special trailer" and is only for use on a trailer.
Regardless of whether you are looking at a P-Metric, Euro-Metric, LT-Metric, Euro-Metric Commercial, T or ST tire the numbers in the size mean the aforementioned thing.
Width
The starting time number to appear in your tire size information is the width, in millimeters, of the correct tires for your vehicle: P225/70R16 91S.
Tire width always refers to the measurement from one sidewall to another. Thus, a tire with the measurement "P225" is for a passenger vehicle and has a nominal width of 225 millimeters.
Aspect Ratio
After the slash marking, the next number you see is for the tire'south attribute ratio, which essentially tells you lot how alpine your tire'southward profile is: P225/70R16 91S. Aspect ratios are delivered in percentages. Tire makers calculate the attribute ratio by dividing a tire'due south height off the rim by its width. If a tire has an attribute ratio of 70, information technology ways the tire's height is 70% of its width.
Lower aspect ratio tires, such as a sixty series, by and large offering vehicle handling performance advantages over higher attribute ratio tires, such as a 75 series, but a typical trade off can be ride harshness.
Structure
Afterward the attribute ratio comes a letter that indicates the type of internal structure maintaining your tire'south stability: P225/70R16 91S.
There are 2 types of construction that you may run across on the sidewall of a tire:
- R – Radial
- D or "B" or "-" – Diagonal or Bias Ply
Radial tires are the most mutual tires on the road in the United States today; thus "R" will usually exist shown in the tire size designation. Radial construction means the tire'due south internal ply cords are oriented in a radial direction, from 1 bead over to the other, substantially perpendicular to the direction of rotation. Yous may as well occasionally run across RF indicating a run flat tire or ZR indicating a tire that is a speed rating college than V.
Rim Diameter
The next number is the diameter code, in inches, of the rim onto which the tire tin be mounted. For example, a tire with the P225/70R16 91S would fit a rim with a 16-inch diameter.
Load Alphabetize
Load alphabetize tin can be a confusing field of study because there are so many different caveats, but we volition try to explicate everything here.
The side by side effigy after the rim size in the sequence is your tire'southward load index, which tells us how much weight, in pounds, the tire tin support when fully inflated: P225/70R16 91S
We phone call information technology the load "index" because the number doesn't tell u.s.a. the precise number of pounds the tire tin carry, at least not by itself. Notwithstanding, the number does represent to a specific load capacity listed in an index. Commencement with 1 and ending with 150, numbers in the load index represent carrying capacities of 99 to 7385 lbs.
There are two types of load types for passenger tires though, Standard Load and Actress Load. If a tire is Standard Load there volition be no markings indicating it but if it is Actress Load the letters XL volition appear after the size and load index.
Standard Load Euro-Metric: 215/55R17 94V
Extra Load Euro-Metric: 215/55R17 98V XL
Rider machine tires like P-Metric and Euro-Metric will only have one load index number where LT-Metric and Euro-Metric Commercial (C-Type) volition have two numbers separated by a slash. The first number is the load index if the tire is used in a single awarding, the second number is the load alphabetize if the tire is used in a dual application. Passenger blazon tires cannot be used in a dual awarding. Low-cal truck tires will also have a Load Range that is indicated by a alphabetic character, such as Load Range E. Load Range is an older term that is all the same commonly used in the industry so you lot may hear your tire dealer reference it just the load index numbers are the all-time way to ensure you accept the proper tire.
I important merely often misunderstood facet about load index is that the load index numbers betwixt standards organizations (P-Metric vs Euro-Metric) are not necessarily on the same scale. Meaning that two tires in the two unlike systems that take the same load alphabetize number could accept unlike maximum load capacities. This is why it'southward of import to not only expect at the load index number but also verify the bodily load capacity.
Speed Rating
The final figure in a tire size sequence is the speed rating, which is indicated past a letter: P225/70R16 91S. Simply as your load index number corresponds to a specific load, your speed rating letter corresponds to a particular speed capability based on a standardized laboratory exam.
For case, a tire with speed rating "S" is rated for up to 112 mph, while a tire rated "R" is up to 106 mph. Recollect that this isn't a recommended cruising speed. Of form, you lot should always follow legal speed limits on roadways.
Replacement tires must have the same or higher speed rating as the vehicle's Original Equipment to maintain vehicle speed capability. If a vehicle has tires with unlike speed ratings, information technology is the speed rating of the "slowest" tire that dictates the vehicle acme speed.
Flotation Sizing
There is one last sizing blazon that you should know virtually, especially if y'all are in the market for off road tires for a light truck or SUV. It'due south called a Flotation size and the numbers in this sizing format are very different from the Metric formats. Flotation sized tires are like to LT-Metric tires in application except for a few important points. Number i, they cannot exist used in dual applications and number ii, an equivalent size tire may have dissimilar load capacity than its LT-Metric counterpart.
Overall Diameter
The first number in the Flotation tire size is the overall bore in inches. Pretty direct frontward.
Section Width
The second number is the section width (sidewall to sidewall) measurement in inches. Once more, adequately simple.
Construction
Afterward the section width comes a letter that indicates the type of internal construction: 33X12.50R17LT 120Q.
This is the same as is found in the metric sizing systems.
There are 2 types of construction that y'all may run into on the sidewall of a tire:
- R – Radial
- D or "B" or "-" – Diagonal or Bias Ply
Radial tires are the most common tires on the road in the U.s. today; thus "R" will ordinarily exist shown in the tire size designation. Radial construction means the tire's internal ply cords are oriented in a radial direction, from 1 bead over to the other, essentially perpendicular to the direction of rotation.
Rim Diameter
The side by side number is the diameter lawmaking, in inches, of the rim onto which the tire can be mounted. For example, a tire with the 33X12.50R17LT 120Q would fit a rim with a 17-inch diameter.
LT type
The letters LT volition be after the Rim Diameter indicating that this tire blazon is intended for Light Truck vehicles similar to the LT-Metric and Euro-Metric Commercial (C-Type) tires.
Load Index and Speed Rating
Load Index and Speed Rating have the same significant and format as the tires using the metric sizing system. Note that since flotation tires cannot be used in a dual application there will be only 1 load alphabetize number instead of two.
Uniform Tire Quality Grading
Some other group of stamping on certain types of tires is the Uniform Tire Quality Grading or UTQG. This grading and stamping is required for passenger car tires (i.due east. P-metric and Euro-metric) in the all season and summertime categories. Dedicated winter tires, Calorie-free Truck (LT-Metric, Euro-Metric Commercial, Flotation) and Motorcycle tires are excluded from this requirement.
Quality grading is designed to make the tire purchase conclusion easier for you. Ideally, the arrangement is intended to provide simple, comparative data then you can make an intelligent buying conclusion. However, the ratings are based upon test results achieved under special atmospheric condition. This means information technology'south possible to misinterpret the comparative data as it relates to your individual driving habits, weather condition, etc. Yous should withal rely on your service or tire professional for assistance.
Quality grading designates the comparative performance levels of a tire based on regime-specified tests but commissioned by the individual tire manufacturers. All tire manufacturers are required to grade regular and all-season passenger tires in iii categories:
UTQG
- Treadwear
- Traction
- Temperature
Treadwear
The treadwear course is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course for vi,000 miles (9,600 km). For example, a tire graded 150 would vesture one and a half times likewise on the government form every bit a tire graded 100. However actual tire operation depends on driving habits, route characteristics, service practices, and other factors that can influence the outcome.
Traction Grades AA, A, B and C
The traction grades from highest to lowest are AA (the highest), A, B and C. They represent how well tires stop on wet pavement equally measured under controlled weather condition on specified government examination surfaces of asphalt and concrete. C-rated tires will take the lowest traction performance.
Warning: THE TRACTION Course ASSIGNED IS BASED ON A WET BRAKING (STRAIGHT Alee) TRACTION TEST AND DOES NOT INCLUDE CORNERING (TURNING) TRACTION.
Temperature Grades A, B and C
The temperature grades A, B, and C represent the tire'south resistance to the generation of rut and its ability to dissipate heat when tested under controlled weather on a specified indoor laboratory test wheel. Sustained high temperature tin can crusade the tire'south material to degenerate and reduce tire life, and excessive temperature tin can lead to sudden tire failure. The course C corresponds to a operation level all rider car tires must meet under the Federal Motor Vehicle Safe Standard No. 109. Grades A and B represent higher levels of performance on the laboratory test wheel than the minimum required by law.
WARNING: THE TEMPERATURE GRADE IS ESTABLISHED FOR A TIRE THAT IS PROPERLY INFLATED AND NOT OVERLOADED. EXCESSIVE SPEED, Nether INFLATION, OR EXCESSIVE LOADING, EITHER SEPARATELY OR IN COMBINATION, CAN Crusade Estrus BUILDUP AND POSSIBLE TIRE FAILURE.
DOT Quality Grades
All passenger car tires must adjust to other federal requirements in addition to these grades.
A History of Innovation
Learn nearly our mission, our achievements, and our ongoing commitments
harrickssoments62.blogspot.com
Source: https://www.bridgestoneamericas.com/en/company/safety/choosing-tires/determining-tire-size