The wheels that came installed on your vehicle are designed to perfectly fit your vehicle’s suspension, gearing, and bodywork which can affect ride quality and vehicle performance. But that doesn’t mean you can’t have different wheels or rims installed on your car or truck. To understand what wheels will work for your vehicle, we’ll take a look at rim sizes and some basic measurements.
There are many reasons you might want to switch out your rims. Maybe you want an extra set of wheels and tires for easy installation every winter, or you’re looking for added performance and handling. You might even be going for a specific look, including sleek and stylish or rugged and cool. Whatever your reason, it’s important to note that getting the wrong wheel setup could cause a vibration, or some rubbing on suspension components or vehicle body parts.
Les Schwab Tip: Before you change the tire sidewall height, tread width, or rim size on your vehicle, talk to the experts first. We’ll help translate the difference in RPM, tire speed, load index, and speed rating and how it will or will not fit with your vehicle’s suspension, gearing, and bodywork.
First, start with the wheel size for your vehicle. You can find that on the sidewall of the tires on your original wheels or the inside frame of the driver’s door. Check out Tire Size Explained (Reading the Sidewall) for more.
The wheel diameter (in inches or millimeters) is the fifth set of numbers and letters. What do rim size numbers mean? This number represents the distance between the two bead seat areas where the tire is sealed onto the wheel.
The wheel size also includes its width and offset. The width is the distance from each bead seat (from inside to the outside). The offset determines how the wheel and tire set aligns with the wheel well.
The offset is how far inward or outward the mounting surface is in reference to the center-line of the wheel.
The center-line is calculated by simply dividing the wheel into two equal halves. Les Schwab has the tools to accurately measure your center-line.
The offset is how far inward or outward the mounting surface is in reference to the center-line of the wheel.
Here's how offset determines the look of your rims. If the hub mounting surface is in front of the center-line, your rims and tire will be pulled inward. This is called positive offset.
If they are behind the centerline, your rims and tire will stick out from the body of the vehicle. This is negative offset.
Les Schwab Tip: Measuring the offset on your vehicle is difficult without removing the tire and wheel. Consult the pros to get the right fit.
To ensure a set of rims fit properly on your vehicle, you’ll need the hub size on your car or truck as well as the wheel center bore measurement and number of wheel studs (as well as the distance between those studs).
Les Schwab has those measurements for your vehicle, including bolt patterns.
Most vehicles come with a 4-, 5-, 6-, or 8-lug pattern. These bolt patterns, which are specifically spaced, help narrow your wheel or rim choices. While counting the number of bolts on your vehicle is important before buying a set of rims, it’s vital the wheels you choose match the spacing between the wheel studs on your vehicle.
To measure a 4-lug pattern on a set of rims, measure from the center of two holes across from each other. For a 5-lug pattern, measure from the outside of one wheel stud hole and the center of the opposite. And for 6- and 8-lug patterns, measure from the center of one hole to the center of the opposite wheel stud hole. You’ll either need this measurement in inches or millimeters, depending on the wheel manufacturer.
Remember, there’s no need to take these measurements on your own. The pros at Les Schwab do it every day and can ensure you get the right rims for your vehicle.
At Les Schwab, we take pride in our custom wheel expertise. Stop by and ask about new wheels for your vehicle. We’ll show you all of your options, whether you’re going for a new look, a boost in performance, a new set of wheels for your winter tires, or simply as a replacement of your current set.
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Home > Company > Tire Safety > Choosing Tires > Determining Tire Size
Once you have determined it’s time to buy tires, you’ll need to know what size tires are correct for your vehicle. Depending on what you drive, you may be interested in how to find the right tire for your…
This information is usually inside your car’s doorjamb, in your owner’s manual.
To ensure your current tire or a replacement tire you may be looking at matches your vehicle’s requirements, it will be good for you to understand how tire sizing works. You may have never paid attention to the string of numbers and letters on every tire, but it’s a gold mine of information.
If you’re unsure of how to read tire measurements from your tire walls, the information and graphics below will tell you how to read tire size, understand and interpret it. If you decide you want to substitute a new size or tire type, consult an authorized tire retailer who can expertly advise you, because many optional tire sizes may have different load capacities and could require wheels of a different rim width or diameter and different inflation pressure.
Not sure you need new tires? Our Tire Replacement Guidance article will help you determine whether it’s time to retire your tires.
Most passenger 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 see 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 car” tire type. For Euro-Metric there will be no preceding letter before the number sequence begins: 225/70R16 98H. Euro-Metric is a designation standardized by the European Tyre and Rim Technical Organization for a “passenger car” 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 light duty pickup trucks.
If your vehicle is an SUV, Pickup truck or van, you might see a different type of size designation on your placard that is specific for heavy duty light trucks and vans, especially common on ¾ ton and larger pickup trucks and vans. There are two common 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 different 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 E. Notice that there are two load index numbers and a Load Range, see the section on Load Index for more info. LT-Metric is a designation standardized by the Tire and Rim Association for a “light truck” type tire. Euro-Metric Commercial or C-Type tires will look very similar to a passenger Euro-Metric size except that there will be a “C” right after the rim size: 23/65R16C 121/119R. Notice that the C-type tires also have 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 usually only specified by a vehicle manufacturer on vehicles exceeding a certain load capacity.
Other types of tires that fall into the Metric sizing type are Temporary Spares, they start with “T”.
If you see 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 same thing.
The first 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.
After the slash mark, the next number you see is for the tire’s aspect ratio, which essentially tells you how tall your tire’s profile is: P225/70R16 91S. Aspect ratios are delivered in percentages. Tire makers calculate the aspect ratio by dividing a tire’s height off the rim by its width.
If a tire has an aspect ratio of 70, it means the tire’s height is 70% of its width.
Lower aspect ratio tires, such as a 60 series, generally offer vehicle handling performance advantages over higher aspect ratio tires, such as a 75 series, but a typical trade off can be ride harshness.
After the aspect ratio comes a letter that indicates the type of internal construction maintaining your tire’s stability: P225/70R16 91S.
There are two types of construction that you may see on the sidewall of a tire:
Radial tires are the most common tires on the road in the United States today; thus “R” will usually be shown in the tire size designation. Radial construction means the tire’s internal ply cords are oriented in a radial direction, from one bead over to the other, essentially perpendicular to the direction of rotation.
You may also occasionally see RF indicating a run flat tire or ZR indicating a tire that is a speed rating higher than V.
The next number is the diameter code, in inches, of the rim onto which the tire can be mounted. For example, a tire with the P225/70R16 91S would fit a rim with a 16-inch diameter.
Load index can be a confusing subject because there are so many different caveats, but we will try to explain everything here.
The next figure after the rim size in the sequence is your tire’s load index, which tells us how much weight, in pounds, the tire can support when fully inflated: P225/70R16 91S
We call it the load “index” because the number doesn’t tell us the precise number of pounds the tire can carry, at least not by itself. However, the number does correspond to a specific load capacity listed in an index.
Beginning 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 Extra Load. If a tire is Standard Load there will be no markings indicating it but if it is Extra Load the letters XL will appear after the size and load index.
Standard Load Euro-Metric: 215/55R17 94V
Extra Load Euro-Metric: 215/55R17 98V XL
Passenger car tires like P-Metric and Euro-Metric will only have one load index number where LT-Metric and Euro-Metric Commercial (C-Type) will have two numbers separated by a slash. The first number is the load index if the tire is used in a single application, the second number is the load index if the tire is used in a dual application. Passenger type tires cannot be used in a dual application. Light truck tires will also have a Load Range that is indicated by a letter, such as Load Range E. Load Range is an older term that is still commonly used in the industry so you may hear your tire dealer reference it but the load index numbers are the best way to ensure you have the proper tire.
One important but often misunderstood facet about load index is that the load index numbers between standards organizations (P-Metric vs Euro-Metric) are not necessarily on the same scale. Meaning that two tires in the two different systems that have the same load index number could have different maximum load capacities. This is why it’s important to not only look at the load index number but also verify the actual load capacity.
The final figure in a tire size sequence is the speed rating, which is indicated by a letter: P225/70R16 91S. Just 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 test.
For example, a tire with speed rating “S” is rated for up to 112 mph, while a tire rated “R” is up to 106 mph. Remember that this isn’t a recommended cruising speed. Of course, you 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 different speed ratings, it is the speed rating of the “slowest” tire that dictates the vehicle top speed.
There is one last sizing type that you should know about, especially if you are in the market for off road tires for a light truck or SUV. It’s called a Flotation size and the numbers in this sizing format are very different from the Metric formats. Flotation sized tires are similar to LT-Metric tires in application except for a few important points. Number one, they cannot be used in dual applications and number two, an equivalent size tire may have different load capacity than its LT-Metric counterpart.
The first number in the Flotation tire size is the overall diameter in inches.
Pretty straight forward.
The second number is the section width (sidewall to sidewall) measurement in inches. Again, fairly simple.
After 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 two types of construction that you may see on the sidewall of a tire:
Radial tires are the most common tires on the road in the United States today; thus “R” will usually be shown in the tire size designation. Radial construction means the tire’s internal ply cords are oriented in a radial direction, from one bead over to the other, essentially perpendicular to the direction of rotation.
The next number is the diameter code, 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.
The letters LT will be after the Rim Diameter indicating that this tire type is intended for Light Truck vehicles similar to the LT-Metric and Euro-Metric Commercial (C-Type) tires.
Load Index and Speed Rating have the same meaning 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 one load index number instead of two.
Another 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.e. P-metric and Euro-metric) in the all season and summer categories.
Dedicated winter tires, Light Truck (LT-Metric, Euro-Metric Commercial, Flotation) and Motorcycle tires are excluded from this requirement.
Quality grading is designed to make the tire purchase decision easier for you. Ideally, the system is intended to provide simple, comparative data so you can make an intelligent buying decision. However, the ratings are based upon test results achieved under special conditions. This means it’s possible to misinterpret the comparative data as it relates to your individual driving habits, conditions, etc. You should still rely on your service or tire professional for assistance.
Quality grading designates the comparative performance levels of a tire based on government-specified tests but commissioned by the individual tire manufacturers. All tire manufacturers are required to grade regular and all-season passenger tires in three categories:
UTQG
Treadwear
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 course for 6,000 miles (9,600 km).
For example, a tire graded 150 would wear one and a half times as well on the government course as a tire graded 100. However actual tire performance depends on driving habits, road 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 as measured under controlled conditions on specified government test surfaces of asphalt and concrete. C-rated tires will have the lowest traction performance.
WARNING: THE TRACTION GRADE ASSIGNED IS BASED ON A WET BRAKING (STRAIGHT AHEAD) 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's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel.
Sustained high temperature can cause the tire’s material to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The grade C corresponds to a performance level all passenger car tires must meet under the Federal Motor Vehicle Safety 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, UNDER INFLATION, OR EXCESSIVE LOADING, EITHER SEPARATELY OR IN COMBINATION, CAN CAUSE HEAT BUILDUP AND POSSIBLE TIRE FAILURE.
DOT Quality Grades
All passenger car tires must conform to other federal requirements in addition to these grades.
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sportek.in.ua Nikolaev bicycle shop "Sportek"
Published: 04/07/2017
Edited: 07/15/2018
From time to time the question arises: “What is the diameter of the bicycle wheels?”
Most often, it pops up if a tire has broken through or new tires are needed for the wheel of an old bicycle. And to the seller’s question “What wheel does your bike have?” Only one answer comes to mind: “round”.
First of all, you need to define the concept of wheel diameter .
For most ordinary people, this is the diameter of the wheel at the outer (outer) border of the tire.
But there is also the concept of rim fit size - this is the diameter of the rim or tire itself along the inner border.
Therefore, it would be a good idea to first understand the tire marking systems adopted in the world in order to speak the same language with the bike shop salesperson.
You can read about this in the article "Bicycle tires: sizes, marking types and interchangeability" on our website.
For the sake of brevity, here is a figure explaining what is measured in each labeling system. Therefore, it is important to understand what we measure and what we want to find.
When choosing a new rubber, be guided by it. If there is no tire with exactly the same marking, look at the interchangeability table and select the right size in another marking.
If a new tire is needed a little wider or narrower, check the tire and rim width chart.
If in doubt, talk to the salesperson. He will tell you if it is right for you, both in terms of size, tread, riding style and what kind of roads you want to ride.
This can be done by measuring the radius and multiplying it by two.
For younger students reading this article, I remind you that one diameter consists of two radii.
Only you need to measure strictly from the center of the sleeve, and not from its edges. When measuring, the bike should stand vertically, and the tape measure, putting one end to the ground, keep the same strictly vertically, and not along the spokes of the wheel . Only such a measurement will give the correct value.
The wheel diameter itself can be measured in the same way.
The main thing is to accurately determine its upper cut. To do this, you can take a level and attach it to the top of the tire, and, holding it strictly horizontally, determine the desired size from the tape measure.
After that, we convert it from mm to inches. To do this, divide it by 25.4 (1 inch = 25.4 mm) and calculate the size in inches. The result can be rounded up to standard inch wheel sizes.
For example, if the measurement is 720 mm, divide by 25.4 to get 28.346 inches. So, most likely, the actual size of the wheel, taking into account the accuracy of the calculations, is 28”.
In principle, the rim diameter can also be measured in the same way.
Just pay attention to the difference between what is measured on the outside of the tape measure and the fit size of the rim.
How to calculate the circumference of a bicycle wheel is described on our website in a separate article (Second method).
And knowing it, it is easy to calculate the diameter. To do this, the circumference in millimeters must be divided by the number "Pi" (3.14). Once you get the diameter in mm, divide it by 25.4 to get the diameter in inches. Similarly to the previous paragraph, the result will have to be rounded to the nearest whole number in inches. The more accurate all measurements, the more accurate the result and the less rounding.
Comments (2)
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Replacing car rims is not an annual procedure.
The condition of domestic roads, the consequences of an accident, many years of mileage - no matter what negative factors affect your wheels, the overall final result: replacement. When selecting new disks, it is necessary not only to determine the type of product, but also to take into account all the significant parameters of the disk. And here the questions arise before the car owner: how to find out the width of the rim of the disk, how to find out the diameter of the hub on the disk and other important characteristics.
Your vehicle may be fitted with rims that match exactly the model of your vehicle. If you spend a significant amount of money on products with inadequate performance, you run the risk of experiencing the following problems:
disks simply do not fit in size, they will be impossible to install;
installation is possible, but soon there will be a negative impact on the technical condition of the car and / or road safety.
Don't waste your money and, more importantly, don't risk your own safety. When buying new discs, immediately select the product that is most suitable for your car in all basic parameters. This approach will ensure trouble-free movement, as well as long-term trouble-free operation of the suspension and chassis as a whole.
What characteristics should the car owner be interested in in the first place? The main significant parameters of rims:
Disc diameter - the mounting fit diameter of the annular / outer part of the rim. Designated in inches.
Disc width, wheel rim width. Specifies the width of the tire to be installed. The indicator is indicated in inches.
DIA is the diameter of the hole for the wheel hub. The value is in mm.
ET - disc offset in mm. Determines the depth of wheel recession in the car arch.
Number of mounting holes.
It must exactly match the nominal value for reliable fixation of the car wheel on the hub.
PCD - diameter of mounting holes. With respect to this quantity, high measurement accuracy is required! Deviations are not allowed.
Some values are traditionally measured in inches, others in millimeters. How not to get confused, how to find out the width of the disk in inches or the diameter of the hole on the disk, if you do not do this work daily? Finding, determining or accurately measuring the necessary indicators is a difficult task for a person who is far from the car service industry.
Is it really that complicated? Let's take a closer look and answer questions from motorists.
It is usually not necessary to measure all the parameters yourself. But how can you find out the width of the rim of an alloy wheel or the diameter of a car wheel without taking measurements? Auto manufacturers indicate the required parameters on the original branded discs.
The marking is standard, the same for steel and alloy wheels.
Remove the spare tire from the trunk or remove the wheel from the car. Read the inscriptions, most often on the inside of the disc. As a rule, 3 main parameters are indicated there: diameter, width and reach. For example: 5.5J x 13, where the first value 5.5J is the width of the disc in inches, and the second is the diameter, also in inches. The inscription ET35: the departure value in millimeters is 35. Instead of ET, the designation OFFSET or DEPORT is found - it depends on the country of origin.
It can also be marked, for example, d54.1, which means DIA - the size of the hole for the hub is 54.1 mm. This inscription answers the question how to find out the inner diameter of the disc and even how to find out the size of the hub on the disc - look for such a marking, this is important.
If numbers are present, say 5x120, then you know the number of seat bolts (5) and PCD is the diameter of their location (120 mm).
It is even easier for the owner of the car if he has the owner's manual for the vehicle. The algorithm of actions is very simple: open, study, select new disks in accordance with the manufacturer's recommendations. It is almost impossible to make a mistake in this case.
However, not all motorists are so fortunate. Let's say there are no instructions, the car is old, and non-native disks were installed by the previous owner - then there is no information in principle. It's OK. There is always a back-up plan for this. Namely, independent action.
Taking measurements yourself is not as difficult as it seems.
The easiest way to count the number of mounting holes is from 3 to 6.
Using a tape measure, ruler or caliper on a disassembled wheel, you can measure the parameters of the diameter of the central hole, the width of the disc.
PCD parameter: how to find out the diameter of the holes on the discs? First, measurements are taken with a caliper, then calculations are made using special formulas.
In the table you can see which PCD values apply to different brands of passenger cars.
PCD value in mm | Car brand |
| 98 | Citroen, Fiat, Alfa-Romeo, LADA, Lancia, Peugeot, Skoda, Seat |
| 100 | Audi, Cooper, BMW, Chrysler, Citroen, Chevrolet, Daewoo, Daihatsu, Fiat, Hyundai, Honda, Jeep, Kia, Mitsubishi, Nissan, Mazda, Opel, Proton, Renault, Rover, Subaru, Peugeot, Skoda, Seat, Suzuki, Volkswagen, Toyota |
| 108 | Audi, Ford, Citroen, Mazda, Land Rover, Peugeot, Jaguar, Renault, Volvo, Saab |
| 110 | Opel, Fiat, Alfa-Romeo, Saab |
| 112 | Audi, Ford, Chrysler, Mercedes-Benz, MCC-Smart, Skoda, Volkswagen, Seat |
| 114. | Chevrolet, Citroen, Chrysler, Daewoo, Daihatsu, Dodge, Jeep, Fiat, Ford, Hyundai, Honda, Lexus, Kia, MCC-Smart, Land Rover, Mitsubishi, Mazda, Nissan, Peugeot, Rover, Renault, Subaru, Suzuki, Volvo , Toyota |
| 115 | Chrysler, Chevrolet, Opel |
| 118 | Citroen, Nissan, Fiat, Peugeot, Renault, Opel |
| 120 | BMW, Volkswagen, Hyundai |
| 120.7 | Jaguar |
Certain parameters can be subject to certain deviations without adversely affecting vehicle handling and
suspension condition.
Disc diameter. Alloy wheels are allowed 1 inch oversize.
Disc width. Tolerance is 0.5 inches.
DIA - The size of the center hole should ideally match the diameter of the hub. Permissible deviation up to +0.
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