NEWS

WHEEL TECH: Proper Lug Nuts or Lug Bolts[12/06/2017]

While many aftermarket alloy wheels are designed to use your car's original lug nuts or bolts, others require new hardware. It may be something as critical as differences in the wheel's lug seat design as shown below, or something as simple as shorter lug heads to allow the wheel's center caps to fit. If your new wheels require new hardware, your invoice will list the appropriate quantity identified by our part description, beginning with an "N" for lug nuts or a "B" for lug bolts followed by the size, pitch, seat design, length and the appropriate lug wrench socket size.

Note: Keep a set of your vehicle's Original Equipment lug nuts or bolts in the trunk just in case you ever need to use your factory spare tire, which must always be installed with the Original Equipment lug hardware.

TIRE TECH: Storing Tires[11/06/2017]

Since heat and exposure to the elements are the important factors that influence a tire's aging process, drivers can prolong their tire's life by minimizing their impact. Here are some tips for storing tires that will not be used continuously.

Don't store a vehicle with weight on its tires for extended periods of time. Long-term inactivity is more harmful to tires than weekly drives that flex the tires and help maintain oil dispersion within the rubber compounds.
Keep the tires out of direct sunlight whenever possible. The sun's ultraviolet rays and radiant heat are detrimental to rubber. We have used a pyrometer to measure tires that were simply sitting in direct sunlight on a parked vehicle. Surprisingly those tires' temperatures measured 135° Fahrenheit on their surface.
Before storing, use a tire brush to clean each tire with soap and water to remove brake dust, dirt and grime. If the tires are still mounted on wheels, use a wheel brush to clean the wheels with an approved cleaner as well. Dry with a towel and let any remaining moisture thoroughly evaporate.
DO NOT APPLY ANY TIRE DRESSINGS. Tire compounds are formulated to resist ozone cracking or weather checking.
Place each clean and dry tire in its own large, opaque, airtight plastic bag (such as lawn and garden bags) for storing. Avoid allowing any moisture to remain and remove as much air as practical (some drivers even use a vacuum cleaner to draw out as much as possible). Close the bag tightly and tape it shut. This places the tire in its own personal mini-atmosphere to help reduce oil evaporation.
While Seasonal Tire Totes make it neater to store tires, easier to carry tires and reduce the possibility of depositing brake dust, dirt and grime in the trunk or on the back seat during transportation, Seasonal Tire Totes are not airtight nor designed to prevent exposure to the atmosphere. The recommended solution would be to place each clean tire and wheel into the airtight plastic bag and then cover the sealed bag with a Tire Tote.
If you choose not to store white letter/white stripe tires in plastic bags, it is important they be stored or stacked white-to-white and black-to-black to prevent staining the white rubber. The black rubber used on the tires' white letter/white stripe side is compounded differently than the black rubber used on the opposite side. A layer of non-staining black rubber covers the white rubber on the tire's white side to prevent oils in the tire from migrating into the exposed white rubber and discoloring it; however the black sidewall uses standard rubber. Stacking all tires white sidewall up will allow the oils from each tire's black sidewall to migrate into the white rubber of the tire below it.
Place the tires in a cool, dry location. It is better to store tires in a dry basement or climate-controlled workshop than in a standard garage, storage shed, hot attic or outdoors. While basement and shop surroundings tend to remain cool and dry, conditions found in typical garage, shed, attic and outdoor locations often include a wide range of hot and cold temperatures, as well as seasonal precipitation and humidity.
Keep the tires away from sources of ozone. Electric motors that use contact brushes generate ozone. Keep your tires away from the furnace, sump pump, etc.
While tires will age somewhat regardless of what precautions are taken, these procedures will help slow the process compared to taking no precautions at all.

WHEEL TECH:What is an Alloy Wheel?[10/06/2017]

Alloy metals provide superior strength and dramatic weight reductions over ferrous metals such as steel, and as such they represent the ideal material from which to create a high performance wheel. In fact, today it is hard to imagine a world class racing car or high performance road vehicle that doesn't utilize the benefits of alloy wheels.

The alloy used in the finest road wheels today is a blend of aluminum and other elements. The term "mag wheel" is sometimes incorrectly used to describe alloy wheels. Magnesium is generally considered to be an unsuitable alloy for road usage due to its brittle nature and susceptibility to corrosion. (Flammability doesn't help either!)

TIRE TECH: Determining the Age of a Tire[07/06/2017]

When it comes to determining the age of a tire, it is easy to identify when a tire was manufactured by reading its Tires Identification Number (often referred to as the tire's serial number). Unlike vehicle identification numbers (VINs) and the serial numbers used on many other consumer goods (which identify one specific item), Tire Identification Numbers are really batch codes that identify the week and year the tire was produced.

The U.S. Department of Transportation (DOT) National Highway Traffic Safety Administration (NHTSA) requires that Tire Identification Numbers be a combination of the letters DOT, followed by eight to thirteen letters and/or numbers that identify the manufacturing location, tire size and manufacturer's code, along with the week and year the tire was manufactured.

"When it comes to determining the age of a tire, it is easy to identify when a tire was manufactured by reading its Tire Identification Number (often referred to as the tire's serial number)."

Tires Manufactured Since 2000
Since 2000, the week and year the tire was produced has been provided by the last four digits of the Tire Identification Number with the 2 digits being used to identify the week immediately preceding the 2 digits used to identify the year.

Example of a tire manufactured since 2000 with the current Tire Identification Number format:


In the example above:
DOT U2LL LMLR 5107
 51 Manufactured during the 51st week of the year
07 Manufactured during 2007

While the entire Tire Identification Number is required to be branded onto one sidewall of every tire, current regulations also require that DOT and the first digits of the Tire Identification Number must also be branded onto the opposite sidewall. Therefore, it is possible to see a Tire Identification Number that appears incomplete and requires looking at the tire's other sidewall to find the entire Tire Identification Number

 


The use of a partial Tire Identification Number on the one sidewall (shown above) reduces the risk of injury to the mold technician that would have to install the weekly date code on the top sidewall portion of a hot tire mold.

Tires Manufactured Before 2000
The Tire Identification Number for tires produced prior to 2000 was based on the assumption that tires would not be in service for ten years. While they were required to provide the same information as today's tires, the week and year the tire was produced was contained in the last three digits. The 2 digits used to identify the week a tire was manufactured immediately preceded a single digit used to identify the year.

Example of a tire manufactured before 2000 with the earlier Tire Identification Number format:


In the example above:
DOT EJ8J DFM 408
 40 Manufactured during the 40th week of the year
8 Manufactured during the 8th year of the decade

While the previous Tire Identification Number format identified that a tire was built in the 8th year of a decade, there was no universal identifier that confirmed which decade (tires produced in the 1990s may have a small triangle following the Tire Identification Number to identify the decade).

And finally, hold on to your sales receipt. Most tire manufacturer's warranties cover their tires for four years from the date of purchase or five years from the week the tires were manufactured. So if you purchase new tires that were manufactured exactly two years ago they will be covered for a total of six years (four years from the date of purchase) as long as you have your receipt. If you lose your receipt, your tires' warranty coverage will end five years from the week the tire was produced (resulting in the tire manufacturer's warranty coverage ending only three years from the date of purchase in this example).

WHEEL TECH:How We Know What Fits[02/06/2017]

It may seem obvious, but a wheel is comprised of a hub, spokes and rim. These parts work together to create the wheel. The hub is the center portion of the alloy wheels and is what attaches the wheel to the suspension. The spokes radiate out from the hub and attach to the rim. The rim is the outer part of the wheel that holds the tire. While many people refer to wheels as "rims," this is technically incorrect.

Wheels come in all different styles, sizes, bolt patterns and offsets. So how do we know which wheels will fit your vehicle? We can only do this by first knowing your vehicle inside and out. Measuring your vehicle's critical components with sophisticated electronic tools allows our fitment engineers to create extremely accurate drawings of these parts. We do the same for the wheels that we offer and then use Computer Aided Design (CAD) programs to match the wheels to the vehicles. Using these electronic tools we verify numerous different critical areas before a wheel can be listed for a vehicle.

Items We Measure Or Verify In The Upgrade Garage®
Bolt Pattern - Not as simple as 4-lug vs. 5-lug. There are currently 17 different 4- to 5-lug bolt patterns as well as 6- to 8-lug for light truck/SUV.

Centerbore - The wheel must, in most cases, fit the hub of the vehicle precisely, either as a direct fit or with the use of a centering ring.

Hub Interference - Many vehicles have additional items on the mounting surface area that must be considered for wheel applications, these include locating pins and rotor mounting hardware.

Load Capacity - The wheel must have enough load capacity when compared to the gross axle weight rating of the vehicle.

Lug Hardware - By either supplying lug hardware or using the Original Equipment hardware the wheel must be securely fastened to the vehicle.

Suspension Components - The wheel must clear and not interfere with any of the suspension components and their operation on the vehicle.


TIRE TECH: Mixing Tires[30/05/2017]

As a general rule, tires should not be mixed on any vehicle unless specified as acceptable by the tire or vehicle manufacturer. Drivers should avoid mixing tires with different tread patterns, internal constructions or sizes, and use identical tires on all of their vehicle's wheel positions in order to maintain the best control and stability. Additionally, drivers should never mix winter tires with all-season/summer tires, or mix run-flat tires with non-run-flat tires.

This is one of the reasons that it is desirable to have all of a vehicle's tires wear out at the same time. It's confirmation that the vehicle design, driving conditions and maintenance practices worked in unison to equalize tire wear and performance. It also lets drivers know they got their money's worth out of the current tires and allows them to choose a set of replacements that will either maintain the Original Equipment (O.E.) tires' capabilities, or help tune the vehicle's qualities to even better suit their needs.

Unfortunately wearing out all tires at the same time isn't always possible. Sometimes vehicle design, the use of differently sized tires on front and rear axles, insufficient maintenance and/or driving conditions conspire to prevent it from happening.

If a vehicle's tires don't all wear out at the same time, drivers are typically forced to decide whether they should purchase a new set of tires (forfeiting the worth of the two tires not fully worn out) or just a pair of replacements. While purchasing a new set of tires is best because it will maintain the handling balance engineered into the vehicle while restoring poor weather traction, it is also more expensive. And while purchasing a pair of replacement tires reduces immediate expense, it brings with it the options of choosing exact, equivalent or alternative tires.

Of the three, the best choice is to select the exact tire currently on the vehicle. This assures that the tire's physical dimensions, internal construction, tread design and tread compound are equal to the tires being replaced.

The second option is to choose equivalent tires from the same tire performance category that share the same speed rating, handling and traction characteristics of the original tires. While this isn't as desirable as selecting the exact tire currently on the vehicle, it can become necessary when the original tires are no longer available.

The third option, choosing alternative tires, should only be considered as a temporary solution in an emergency situation. Using alternative tires from different tire performance categories, with alternate sizes or different speed ratings can unbalance the vehicle's handling in poor weather or when pushed to the limit in an emergency.

Because tires play such an important role in every vehicle's comfort qualities and handling capabilities, it is always best to drive on tires that are identical in every detail, including tire brand, model, size and remaining tread depth. Anything else involves some type of compromise.

WHEEL TECH:Finishes & Care[29/05/2017]

Once your new wheels and tires are installed, step back and take a good look. The new, sharper appearance will accent your vehicle splendidly. They look great now; but unfortunately, your wheels are often the dirtiest part of your car because they are constantly exposed to the elements (corrosive brake dust, ocean or road salt, stones, cinders and sticky tar).

Cleaning Wheels
Damage caused by prolonged exposure to these elements will void the finish warranty on your wheels. It's important to clean them properly and often.

Here are a few tips on how to maintain a wheel's original splendor.

Before you install them, a coat of wax will help protect your wheels and make them easier to clean.

Treat the finish of your wheels as you would the finish of your car. Most alloy wheels today feature a painted and/or a clearcoat finish. The best way to take care of wheels without damaging their protective finish is by frequently washing them with a mild soap and water solution. Using a tar and bug remover can prevent permanent tar staining. Periodic waxing will protect the wheel's finish from the elements.

Never use abrasive cleansers, steel wool pads or polishing compounds.

Beware of automatic car washes. Some washes use acid cleaners either before or during the wash to remove dirt and grime. Others use stiff brushes for cleaning wheels and tires. Both of these processes could harm your wheel's finish. Wheels with low profile tires can be damaged by the metal tracks used in most car washes. Ask the employees of the car wash about their equipment and procedures before entering the wash.

Never allow your wheels and tires to be steam cleaned. Steam can dull the paint and clearcoat finish on your wheels.

Don't clean hot wheels — wait until they cool. Cleaning wheels while they are hot may cause your mild soap solution to dry too quickly leaving spots or a film of soap on your wheels.

Clean your tires and wheels first, one at a time. Tires and wheels tend to be the dirtiest parts of your vehicle and have a variety of surfaces to clean. So you will want to use the full strength of your hose to initially rinse away all loose dirt and to finally rinse off your soap solution. If you clean your tires and wheels first, you won't expose your washed car to the over spray as you rinse them. Cleaning one at a time focuses your attention and ensures that the soap doesn't dry on one wheel while you're cleaning another. Be sure to use a different sponge on the rest of the car's body to prevent scratching the paint from the particles that may have collected during the wheel cleaning process.

Clean wheels on a regular basis. Your new tires and alloy wheels are like any other valuable investment. Care for them as you would care for your entire vehicle.

TIRE TECH:How to Read Speed Rating, Load Index & Service Descriptions[27/05/2017]

Using a P195/60R15 87S tire size as our example, the 87S at the end of the size represents the tire's service description. A service description identifies the tire's load index and speed rating. Service descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991.


The first two digits (87S) represent the tire's load index and are followed by a single letter (87S) identifying the tire's speed rating.


"Using a P195/60R15 87S tyres size as our example, the 87S at the end of the size represents the tire's service description. A service description identifies the tire's load index and speed rating."


Load Index

P195/60R15 87S - The load index (87) is the tire size's assigned numerical value used to compare relative load carrying capabilities. In the case of our example, the 87 identifies the tire's ability to carry approximately 1,201 pounds.


The higher the tire's load index number, the greater its load carrying capacity.


89 = 1,279 pounds

88 = 1,235 pounds

87 = 1,201 pounds

86 = 1,168 pounds

85 = 1,135 pounds


A tire with a higher load index than that of the Original Equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the Original Equipment tire indicates an equivalent load capacity. A tire with a lower load index than the Original Equipment tire indicates the tire does not equal the load capacity of the original.


Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 126.


Load Index Pounds Kilograms

Load Index Pounds Kilograms

Load Index Pounds Kilograms

70 739 335 89 1279 580 108 2205 1000

71 761 345 90 1323 600 109 2271 1030

72 783 355 91 1356 615 110 2337 1060

73 805 365 92 1389 630 111 2403 1090

74 827 375 93 1433 650 112 2469 1120

75 853 387 94 1477 670 113 2535 1150

76 882 400 95 1521 690 114 2601 1180

77 908 412 96 1565 710 115 2679 1215

78 937 425 97 1609 730 116 2756 1250

79 963 437 98 1653 750 117 2833 1285

80 992 450 99 1709 775 118 2910 1320

81 1019 462 100 1764 800 119 2998 1360

82 1047 475 101 1819 825 120 3086 1400

83 1074 487 102 1874 850 121 3197 1450

84 1102 500 103 1929 875 122 3307 1500

85 1135 515 104 1984 900 123 3417 1550

86 1168 530 105 2039 925 124 3527 1600

87 1201 545 106 2094 950 125 3638 1650

88 1235 560 107 2149 975 126 3748 1700


When looking at light truck (LT) or newer Special Trailer Service (ST) tires, there are two load indexes branded on the sidewall, separated by a forward slash. Using an LT235/75R15 104/101S Load Range C tire as an example, the load index is 104/101. 104 corresponds to 1,984 pounds, and 101 corresponds to 1,819 pounds. So what is the true load carrying capacity of the tire? The answer changes depending on the situation in which the tire is being used.


Since LT tires are commonly used on trucks with dual rear wheels, they are branded with two load indexes. The first number indicates the load carrying capacity if the tire is installed on a truck with a single-wheel rear axle, and the second number applies when the tire is used in a dual rear application.


Though it may seem counterintuitive that a tire is rated to carry less weight when working in tandem with another tire in the dual pair, the purpose is to build in additional reserve capacity should one of the two tires fail, leaving the sole remaining tire to carry the load normally handled by two tires.


Speed Rating

In Germany some highways do not have speed limits and high speed driving is permitted. Speed ratings were established to match the speed capability of tires with the top speed capability of the vehicles to which they are applied. Speed ratings are established in kilometers per hour and subsequently converted to miles per hour (which explains why speed ratings appear established at "unusual" mile per hour increments). Despite the tire manufacturers' ability to manufacture tires capable of high speeds, none of them recommend the use of their products in excess of legal speed limits. The maximum operating speed of a vehicle must be limited to the lowest speed rated tire on the vehicle.


Speed ratings are based on laboratory tests where the tire is pressed against a large diameter metal drum to reflect its appropriate load, and run at ever increasing speeds (in 6.2 mph steps in 10 minute increments) until the tire's required speed has been met.


It is important to note that speed ratings only apply to tires that have not been damaged, altered, under-inflated or overloaded. Additionally, most tire manufacturers maintain that a tire that has been cut or punctured no longer retains the tire manufacturer's original speed rating, even after being repaired because the tire manufacturer can't control the quality of the repair.


Over the years, tire speed rating symbols have been marked on tires in any of three ways shown in the following examples:


225/50SR16 225/50SR16 89S or 225/50R16 89S

Each of these was an acceptable method of identifying speed ratings.


Early tires had their speed rating symbol shown "within" the tire size, such as 225/50SR16. Tires using this type of branding were not to have been produced after 1991.


225/50SR16 112 mph, 180 km/h

225/50HR16 130, 210 km/h

225/50VR16 in excess of 130 mph, 210 km/h


Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire's service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:


L 75 mph 120 km/h Off-Road & Light Truck Tires

M 81 mph 130 km/h Temporary Spare Tires

N 87 mph 140km/h

P 93 mph 150 km/h

Q 99 mph 160 km/h Studless & Studdable Winter Tires

R 106 mph 170 km/h H.D. Light Truck Tires

S 112 mph 180 km/h Family Sedans & Vans

T 118 mph 190 km/h Family Sedans & Vans

U 124 mph 200 km/h

H 130 mph 210 km/h Sport Sedans & Coupes

V 149 mph 240 km/h Sport Sedans, Coupes & Sports Cars


When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of vehicles that have extremely high top-speed capabilities.


W 168 mph 270 km/h Exotic Sports Cars

Y 186 mph 300 km/h Exotic Sports Cars


While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.


225/50ZR16 in excess of 149 mph, 240 km/h

205/45ZR17 88W 168 mph, 270 km/h

285/35ZR19 99Y 186 mph, 300 km/h


When the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below:


285/35ZR19 99Y 186 mph, 300 km/h

285/35ZR19 (99Y) in excess of 186 mph, 300 km/h


As vehicles have increased their top speeds into Autobahn-only ranges, the tire speed ratings have evolved to better identify the tire's capability, allowing drivers to match the speed of their tires with the top speed of their vehicle.


Related Links


Calculating Approximate Tire Dimensions

Contact Patch

Plus Size Wheels & Tires

Tire Size Conversion Chart

Tire Size Guide



WHEEL TECH: Wheel Construction[26/05/2017]

All Wheels Are Round. Or Are They?

Though not enforced, there are quality standards to govern the production of alloy wheels. Some countries though, like Germany and Japan, have government regulations requiring aftermarket wheels to meet certain criteria and ensure proper fit. The United States has taken steps to establish guidelines but it will be some time before they can enact regulation of any kind.


Consequently, all wheels are not made the same. The performance of an alloy wheel is a direct result of the manufacturing technique employed.


We offer a wide range of wheel choices from manufacture's that have adopted the manufacturing processes that meet the strict O.E.M. (Original Equipment manufacturers) requirements. Wheel companies that supply to the O.E.M. market must follow certain procedures during the manufacturing process to maintain the quality and integrity of their product.


"...all wheels are not made the same. The performance of an alloy wheel is a direct result of the manufacturing technique employed."


There are many factors to consider when purchasing an alloy wheel.


What Is a Wheel and What Is a Rim? Are They the Same Thing?

It may seem obvious, but a wheel is comprised of a hub, spokes and rim. Sometimes these components will be one piece, sometimes two or three. The hub is the center portion of the wheel and is what attaches the wheel to the suspension. The spokes radiate out from the hub and attach to the rim. The rim is the outer part of the wheel that holds the tire. While many people refer to wheels as "rims," this is technically incorrect. We'll discuss several ways that wheels are manufactured below.


One-Piece Cast Wheels

This is the most common type of aluminum wheel. The casting of wheels is the process of getting molten aluminum inside a mold to form a wheel. There are different ways this can be accomplished and although it sounds simple, this is truly an art when done properly.


Gravity Casting


Gravity casting is the most basic process of pouring molten aluminum into a mold utilizing the earth's gravity to fill the mold. Gravity casting offers a very reasonable production cost and is a good method for casting designs that are more visually oriented or when reducing weight is not a primary concern. Since the process relies on gravity to fill the mold, the aluminum is not as densely packed in the mold as some other casting processes. Often gravity cast wheels will have a higher weight to achieve the required strength.


Low Pressure Casting


Low pressure casting uses positive pressure to move the molten aluminum into the mold quicker and achieve a finished product that has improved mechanical properties (more density) over a gravity cast wheel. There is a slightly higher production cost over gravity casting, but low pressure casting is the most common process approved for aluminum wheels sold to the O.E.M. market. Some companies offer wheels that are produced under a higher pressure in special casting equipment to create a wheel that is lighter and stronger than a wheel produced in low pressure, but there's a higher cost associated with the process. Low pressure cast wheels offer a good value for the aftermarket while still maintaining strength and a lighter weight.


Spun-Rim, Flow-Forming or Rim-Rolling Technology

This specialized process begins with a low pressure type of casting and uses a special machine that spins the initial casting, heats the outer portion of the casting and then uses steel rollers pressed against the rim area to pull the rim to its final width and shape. The combination of the heat, pressure and spinning create a rim area with the strength similar to a forged wheel without the high cost of the forging. Some of the special wheels produced for the O.E.M. high performance or limited production vehicles utilize this type of technology resulting in a light and strong wheel at a reasonable cost. O.Z. has used this technology for several years in their production of racing wheels for Formula One and Indy cars. O.Z.'s Formula HLT wheel for the aftermarket is an example of a wheel produced using spun-rim technology.


High Light Technology (HLT)

The High Light Technology (HLT) process used in the manufacturing of select O.Z. Racing wheels uses rollers to compress and elongate the material along the barrel of a low-pressure cast aluminum wheel to obtain the desired profile. This process, which is directly derived from O.Z.'s experience in F1, produces wheels that are extremely light and strong.


The flow-forming process and the HLT technologies combine to create mechanical characteristics similar to those of a forged wheel. This permits a dramatic reduction in wheel weight while enhancing structural rigidity vs. a standard cast wheel.


In forged wheels, computer numerically controlled (CNC) mills add the cosmetics and the bolt circle to exacting tolerances.


Forged

The ultimate in one-piece wheels. Forging is the process of forcing a solid billet of aluminum between the forging dies under an extreme amount of pressure. This creates a finished product that is very dense, very strong and therefore can be very light. The costs of tooling, development, equipment, etc., make this type of wheel very exclusive and usually demand a high price in the aftermarket.


Multi-Piece Wheels

This type of wheel utilizes two or three components assembled together to produce a finished wheel. Multi-piece wheels can use many different methods of manufacturing. Centers can be cast in various methods or forged. The rim sections for 3-piece wheels are normally spun from disks of aluminum. Generally, spun rim sections offer the ability to custom-tailor wheels for special applications that would not be available otherwise. The rim sections are bolted to the center and normally a sealant is applied in or on the assembly area to seal the wheel. This type of 3-piece construction was originally developed for racing in the early 1970s and has been used on cars ever since. The 3-piece wheels are most popular in the 17" and larger diameters.


There are now many options for 2-piece wheels in the market. The 2-piece wheel design does not offer as wide a range of application that a 3-piece wheel allows; however, they are more common in the market and the prices start well below the average 3-piece wheel. Some 2-piece wheels have the center bolted into a cast or cast/spun rim section and other manufacturers press centers into spun rim sections and weld the unit together. When BBS developed a new 2-piece wheel to replace the previous 3-piece street wheel, they used the special rim-rolling technology (originally developed for racing wheels) to give the rim section the weight and strength advantages similar to a forged rim. On the high-end of the 2-piece wheel market you can find wheels using forged rims and forged centers. Since these are only sold in small volume and due to the high development and production costs associated with the forging process, they tend to be on the high end of the price scale.

TIRE TECH:How to Read Speed Rating, Load Index & Service Descriptions[17/05/2017]

Using a P195/60R15 87S tires size as our example, the 87S at the end of the size represents the tire's service description. A service description identifies the tire's load index and speed rating. Service descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991.

The first two digits (87S) represent the tire's load index and are followed by a single letter (87S) identifying the tire's speed rating.

"Using a P195/60R15 87S tire size as our example, the 87S at the end of the size represents the tire's service description. A service description identifies the tire's load index and speed rating."

Load Index
P195/60R15 87S - The load index (87) is the tire size's assigned numerical value used to compare relative load carrying capabilities. In the case of our example, the 87 identifies the tire's ability to carry approximately 1,201 pounds.

The higher the tire's load index number, the greater its load carrying capacity.

89 = 1,279 pounds
88 = 1,235 pounds
87 = 1,201 pounds
86 = 1,168 pounds
85 = 1,135 pounds

A tire with a higher load index than that of the Original Equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the Original Equipment tire indicates an equivalent load capacity. A tire with a lower load index than the Original Equipment tire indicates the tire does not equal the load capacity of the original.

Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 126.

Load Index Pounds Kilograms
Load Index Pounds Kilograms
Load Index Pounds Kilograms
70 739 335 89 1279 580 108 2205 1000
71 761 345 90 1323 600 109 2271 1030
72 783 355 91 1356 615 110 2337 1060
73 805 365 92 1389 630 111 2403 1090
74 827 375 93 1433 650 112 2469 1120
75 853 387 94 1477 670 113 2535 1150
76 882 400 95 1521 690 114 2601 1180
77 908 412 96 1565 710 115 2679 1215
78 937 425 97 1609 730 116 2756 1250
79 963 437 98 1653 750 117 2833 1285
80 992 450 99 1709 775 118 2910 1320
81 1019 462 100 1764 800 119 2998 1360
82 1047 475 101 1819 825 120 3086 1400
83 1074 487 102 1874 850 121 3197 1450
84 1102 500 103 1929 875 122 3307 1500
85 1135 515 104 1984 900 123 3417 1550
86 1168 530 105 2039 925 124 3527 1600
87 1201 545 106 2094 950 125 3638 1650
88 1235 560 107 2149 975 126 3748 1700

When looking at light truck (LT) or newer Special Trailer Service (ST) tires, there are two load indexes branded on the sidewall, separated by a forward slash. Using an LT235/75R15 104/101S Load Range C tire as an example, the load index is 104/101. 104 corresponds to 1,984 pounds, and 101 corresponds to 1,819 pounds. So what is the true load carrying capacity of the tire? The answer changes depending on the situation in which the tire is being used.

Since LT tires are commonly used on trucks with dual rear wheels, they are branded with two load indexes. The first number indicates the load carrying capacity if the tire is installed on a truck with a single-wheel rear axle, and the second number applies when the tire is used in a dual rear application.

Though it may seem counterintuitive that a tire is rated to carry less weight when working in tandem with another tire in the dual pair, the purpose is to build in additional reserve capacity should one of the two tires fail, leaving the sole remaining tire to carry the load normally handled by two tires.

Speed Rating
In Germany some highways do not have speed limits and high speed driving is permitted. Speed ratings were established to match the speed capability of tires with the top speed capability of the vehicles to which they are applied. Speed ratings are established in kilometers per hour and subsequently converted to miles per hour (which explains why speed ratings appear established at "unusual" mile per hour increments). Despite the tire manufacturers' ability to manufacture tires capable of high speeds, none of them recommend the use of their products in excess of legal speed limits. The maximum operating speed of a vehicle must be limited to the lowest speed rated tire on the vehicle.

Speed ratings are based on laboratory tests where the tire is pressed against a large diameter metal drum to reflect its appropriate load, and run at ever increasing speeds (in 6.2 mph steps in 10 minute increments) until the tire's required speed has been met.

It is important to note that speed ratings only apply to tires that have not been damaged, altered, under-inflated or overloaded. Additionally, most tire manufacturers maintain that a tire that has been cut or punctured no longer retains the tire manufacturer's original speed rating, even after being repaired because the tire manufacturer can't control the quality of the repair.

Over the years, tire speed rating symbols have been marked on tires in any of three ways shown in the following examples:

225/50SR16 225/50SR16 89S or 225/50R16 89S
Each of these was an acceptable method of identifying speed ratings.

Early tires had their speed rating symbol shown "within" the tire size, such as 225/50SR16. Tires using this type of branding were not to have been produced after 1991.

225/50SR16 112 mph, 180 km/h
225/50HR16 130, 210 km/h
225/50VR16 in excess of 130 mph, 210 km/h

Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire's service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:

L 75 mph 120 km/h Off-Road & Light Truck Tires
M 81 mph 130 km/h Temporary Spare Tires
N 87 mph 140km/h
P 93 mph 150 km/h
Q 99 mph 160 km/h Studless & Studdable Winter Tires
R 106 mph 170 km/h H.D. Light Truck Tires
S 112 mph 180 km/h Family Sedans & Vans
T 118 mph 190 km/h Family Sedans & Vans
U 124 mph 200 km/h
H 130 mph 210 km/h Sport Sedans & Coupes
V 149 mph 240 km/h Sport Sedans, Coupes & Sports Cars

When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of vehicles that have extremely high top-speed capabilities.

W 168 mph 270 km/h Exotic Sports Cars
Y 186 mph 300 km/h Exotic Sports Cars

While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.

225/50ZR16 in excess of 149 mph, 240 km/h
205/45ZR17 88W 168 mph, 270 km/h
285/35ZR19 99Y 186 mph, 300 km/h

When the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below:

285/35ZR19 99Y 186 mph, 300 km/h
285/35ZR19 (99Y) in excess of 186 mph, 300 km/h

As vehicles have increased their top speeds into Autobahn-only ranges, the tire speed ratings have evolved to better identify the tire's capability, allowing drivers to match the speed of their tires with the top speed of their vehicle.
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