Wheel dimension labels and terms of common use include rim diameter, rim width, backspace, offset and bolt circle
- Rim diameter
It is the diameter of the rim's bead seat floor, not the diameter of the outer rim edge. The rim edge, or lip, extends beyond the bead seat area to capture the bead and prevent the bead from slipping off the rim. If we say that a wheel has a 19-inch diameter, we mean that the diameter of the bead seat floor measures 19 inches. The outer rim edge diameter may actually measure 22 inches or so, depending on the design.
- Rim width
It is the distance from the outboard bead seat to the inboard bead seat. Just as with rim diameter, rim width is not measured at the overall width of the wheel (you only should be concerned with the seating width that the wheel offers for the tire beads).
If a wheel is said to be 10 inches wide, the distance between the bead seats is 10 inches. The overall width, measured between the rim outside edges, is immaterial.
It is the distance from the rear face of the wheel center (the face that contacts the hub) to the rim's rear outer edge. In this case, we don't care about the location of the bead seat. Instead, we do want to know how far the outer edge of the rim extends from the center section's hub contact face.
Refers to the location of the center section's hub contact face, relative to the mid-point of the rim width. The mid-point of the rim width is exactly that: If the rim is 10 inches wide from bead seat to bead seat, the mid-point, or halfway mark, would be 5 inches from either bead seat.
If the wheel center section hub contact face is in-line with the rim's midpoint, this is "zero" offset. This would place the center of the tire tread in-line with the axle's hub face.
If the center of the rim is positioned inboard relative to the mounting surface of the hub, this is called "positive" offset (positive offset places the tires on the same axle closer together, creating a narrower track).
If the center of the rim is positioned outboard relative to the hub mounting face, this is called "negative" offset (negative offset places the tires on the same axle further apart, creating a wider track)
- Bolt circle
It is simply a way to measure the "layout" of the wheel fastener holes. If we connect all of the fastener holes by drawing an imaginary circle through the center of each hole, the diameter of that circle is the "bolt circle." This might be 4.5 inches, 4.75 inches, 114mm, etc.
Center bore and Hub centric Rings
The Center bore centers the wheel on the hub of the car. Most wheels are mass produced, and have a large center bore to accommodate several different vehicles. Hub rings are hard plastic rings that link the wheel to the vehicle. It is recommended that you use hub centric rings if there you have a vibration problem. This makes your wheel hub centric by centering the wheel. Without hub rings it is possible to get vibrations even if the wheel and tire package is completely balanced.
The wheel offset is the distance from the hub mounting surface to the centerline of the wheel. There are three types of offsets.
A positive offset means the mounting surface of the wheel is positioned in front of the true centerline of the wheel. Most factory rims will have this type of offset.
When the hub mounting surface is centered within the rim, it is known as a zero offset.
If the hub mounting surface is on the brake side of the center line of the rim, it is considered a negative offset or "deep dish".
Wheel Sizing and Types
Wheel (Rim) Sizing
If you look inside almost any wheel you will find markings that provide you with information on the wheel. How to read the Rim Markings:
For example: 15x6-JJ 114.3-4-33
WHEEL (RIM) TYPES
15 = Rim Diameter
6 = Rim Width
JJ = Flange Shape
114.3 = P.C.D (mm)
4 = Number of bolt holes
33 = Offset (mm)
Wheels can be broken down according to their cross-sectional shape. Below are a few of the main types of rims.
These rims are used on passenger car tires, light truck tires, and the tubeless type of truck and bus tires.
The divided rims are seen on light truck tires, industry vehicle tires, and agricultural vehicle tires.
Wide-Base, Flat-Base Rim
They are only used on truck and bus tires (tube type)
Semi-Drop Center Rim
Used on light truck tires.
A wheel's bolt-circle-diameter is the diameter of an imaginary circle drawn through the center of the wheel's mounting-bolt holes. Different vehicle makes and models have varying bolt patterns.
If the pattern has an even number of mounting holes (four, six or eight lugs) simply measure from the center of one stud hole directly across the center of the wheel to the center of an opposite stud hole.
With a five-lug pattern, measure from the center of one stud hole to the center of the farthest stud hole, skipping the adjacent hole. The resulting measurement is slightly smaller than the actual bolt-circle diameter.
For example, a vehicle with a bolt pattern of (5 x 120) means this vehicle's hub has five bolts or lugs, which measure 120 millimeters apart from one another diagonally. Below is a chart on how to measure bolt patterns. Wheelfire.com has a fitment program that calculates this for you.
Wheel Fitment and Plus Sizing
In accordance with our Fitment Guarantee, Ready Wheels has pioneered a fitment program that ensures 100% proper fitment on your vehicle. Our team is available to offer custom advice in finding the proper styles and fitment of rims and tires. Our staff is constantly at work making sure wheel specifications are compatible with your vehicle. If you have any upgraded brakes or suspensions please contact one of our customer service representatives before you place your order.
Plus sizing your wheel and tire package is intended to enhance vehicle performance and looks by allowing fitment of larger diameter rims and lower profile tires. The idea is that while making these changes, you keep the overall tire diameter within 3% of the original equipment. If you exceed 3% you open the door to lots of other problems.
Plus sizing: Widen the tire, shorten the sidewall, but keep the outer tire diameter the same
Tire and wheel "plus" sizing refers to creating a package that provides a wider tire with a shorter sidewall fitted to a larger diameter wheel that rolls down the road with the same "overall" diameter as the original tire.
This allows you to play with appearance (more wheel face wrapped in lower profile rubber) and performance (shorter sidewalls mean less lateral flex and quicker response, and larger contact patches mean better traction).
The plus-sizing approach has been around for years, and remains a popular and sensible method of road tuning your customer's car.
Plus-Zero does not require a change in wheel sizing. But a simple alteration in tire size can result in a wider section width and shorter sidewall.
Using the original wheel diameter, select a tire that features the same outer diameter as the original, but that offers a wider section and lower aspect ratio. Assuming that you have adequate inner and outer fender and suspension clearance, this will provide a fatter contact patch and improved handling without getting "extreme."
This combo uses a wheel that is one inch larger in diameter than the original wheel. A tire is then selected that mates to that wheel, but provides the same outer diameter as the OE tire. The result: no change in speedometer reading or ABS sensing, but a shorter sidewall and bigger footprint for superior handling, braking and looks. In other words, more wheel, mated to a lower profile tire, equals cooler vibes.
As the term implies, you choose a wheel that features a diameter two inches larger than that of the OE wheel, and join it with a tire that matches the OE tire's outer diameter, but provides a much shorter sidewall and more contact patch capacity.
- Plus-Three and Plus-Four.
By now, you get the idea. You can Plus size depending on the application
As an added note, make sure your customers know what they are getting into with Plus-sizing. As they "Plus-up," the tire sidewall shrinks in height. The shorter the sidewall, the less sidewall flex available -- which translates into a potentially stiffer, thumpier ride.
If the vehicle is intended for daily transport on rough, pothole riddled streets and comfort is paramount, advise them to take it easy. Plus-Zero or Plus-One fitments may be just fine for the situation.
But for a successful plus move, make sure the overall tire diameter equals that of the tire originally installed by the car maker. If you can't match the outer diameter, at least stay as close as you can to avoid inaccurate speed readings and possible interference with anti-lock brakes and traction control systems.
Speaking in general terms, you should be fine if you stay within 2% to 5% of the OEM outer diameter.
Always keep your wheels clean at all times this way you can protect your investment. Do not let dust or dirt sit on your wheels this might destroy the finish. Never use steam cleaners or automatic car washes; they can damage your wheels.
The best product to use is a mild soap, cleaning one wheel at a time. Rinse immediately, this way you don’t get a soap scum buildup. Always wait until your wheels are cool before cleaning them. After the wheels are clean and dry you may add a very light coat of wheel wax to protect your wheels from the elements.
Wheel Installation and Torque
WHY EVERYONE SHOULD TORQUE
Every vehicle has a particular amount of torque, or force, to tighten a lug or bolt when installing a wheel on a car. These numbers are recommended by the manufacturer and can easily be found in any vehicles’ owner’s manual. It is very important to tighten lugs or bolts correctly on the car. If the wheel is not tight enough it will cause vibrations and wobbling of the wheel. On the other hand, if the wheel lug or bolt is too tight, this will but excessive force on the brake assembly and may cause brake damage.
Although it is not required, we strongly recommend that you purchase a high quality torque wrench. The torque wrench will provide you with accuracy up to two-percent clockwise and four-percent counterclockwise. The digital display will show you the torque ranges between five and one hundred ft. and lbs. and will give you the choice of three units of measure between lb., ft. lb., and Nm.
It is recommended that you re-torque your tires after you break them in, this period is the first 50 to 100 miles they are driven on. During that period the tires may compress slightly allowing the lugs to lose some torque. Below are the usual torque requirements depending on the size of the hardware. The hardware is simply the lug or the bolt for the wheel. And the size is imprinted on the metal of the hardware.
||Torque in FT/LB
Most alloy wheels are made in one, two, or three piece construction types.
One piece wheels
are made in a mold as a single piece of metal.
Two piece wheels
are made of two separate pieces (named the center and barrel) that are usually welded or bolted together.
Three piece wheels
are made of three separate pieces bolted together.
Wheels are manufactured in a variety of ways, such as Forging, Low pressure Casting, and Counter pressure Casting.
This 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 very light.
Low Pressure Casting
This is the most common form of rim manufacturing. Liquid metal is poured into a mold and allowed to harden until the finished wheel is cool enough to be taken out of the casting.
Counter Pressure Casting
This method actually sucks the metal into a mold using a vacuum. This reduces impurities making the wheel much stronger than a low pressure cast rim.
Wheel Finishes and Colors
Aftermarket wheel manufacturers provide a wide variety of custom wheels with an array of finishes. They range from the conservative and understated to the flamboyant, “look at me” finishes. This gives us a way to make our vehicle ours with personalization’s that will truly make it unique. Here is a breakdown of all the various finishes.
These have truly become the industry’s standard finish for those looking to add some shine to there vehicle’s look. These have a mirror-like finish that is very durable since it is applied in 3 stages. First a nickel bath, then a copper, and finally the chrome leads to that pristine finish.
While the chrome is always in style, people are starting to follow the new trend of the color-matched finish. Multi-piece wheels allow an infinite amount of custom-paint possibilities as the center section of the wheel can be matched to the same color as your vehicle’s body. While most top of the line 3-piece wheels are available with a painted to match or a complement to the vehicle’s color, there are now more affordable alternatives such as the solid black wheels. These cost less than the chrome, but look more intimidating.
These have yet to really catch on, but you can still find them at select wheel manufacturers. These wheels have the aesthetic look that they were brushed by hand, when actually a machine grains the pattern onto the wheel to give it the visual texture the customer desires. The wheel is then coated to protect the look. You will usually only find the custom brushed wheels sold as three piece sets.
The machine finish has been one of the more recent favorites. The face of the wheel is sanded down to produce a smooth finish that looks satin yet industrial. It is then coated to protect the look.
The two-tone finish is a combination of chrome and color-matched finishes that will give the user the added flair and satisfaction. The finish is done by first taping off selected portions of the wheel, so that the other untaped portion can be sanded down so that it can be painted. Usually you have the choice as to what is painted on the wheel, and whatever you choose, the end results and gratifying. It requires patience and skill to produce, but it’s worth it as you’ll have the best of both worlds.
The silver finish is similar to that found on stock wheels. It comes in a wide array of similar gradients that varies from manufacturer to manufacturer. These are not painted, but powdercoated to achieve its finish. This process is in fact favored over painting because of the greater durability and stronger finish when tested against rocks and other road debris.
This look is produced through the powdercoating using the sputtering process. This process can create a wheel finish that adds much more depth than other finishes. It is much more lustrous than ordinary silver, and can be found on higher-end cars like Lexus and Infiniti. Sputtering is a seven step process that involves a black basecoat. This is followed by lighter gradients all of which are applied at different angles in a step-by-step process until the face of the wheel has the bright luster. Over the life of the wheel, you will notice that the silver will eventually fade into a darker black finish. Though it won’t be what it was the shade of black resembles gun metal, which looks sharp in itself.
ALTERNATE CAPS AND INSERTS
These caps give you the additional option of changing the look of your wheels. First, you must make sure you purchase a set of wheels that are compatible with the alternate caps. Once you do that, popping the faces on and off are a snap. Pop the pressure rings and clips into the center bore and bolt down the ends of each spoke into the bolt holes. In less than ten minutes, you’ll have a brand new look without having to buy a whole new set of wheels. Alternate caps come in black and color-matched to accentuate your vehicle.
Also available now on many wheels are inserts. Inserts are made of similar materials as caps, but they do not cover a large portion of the wheel. Instead, inserts are smaller pieces that accent the wheel. Many times these inserts go between spokes to give the wheel a different look. As with caps, inserts are also paintable and are easy to put on and take off the wheel.
WHO SHOULD PAINT MY WHEELS?
First off, go to someone you trust, painting wheels requires a bit of skill, and patience is a virtue. Ask to see at least some pictures of previous work before handing your wheels over. Be sure to check for overspray, any scuffs when you get them back, and just be sure that you trust them.
The aftermarket wheels industry has evolved over the years; there have been several methods and materials when it comes to manufacturing wheels. Everything from aluminum alloy to steel and magnesium alloy has been used to forge wheels. Aluminum alloy wheels are broken into single-piece wheels and multi-piece wheels. Single-piece, or one-piece wheels are made in a variety of ways. Gravity casting, low-pressure casting, tilt die-casting, and forge are the ways to make a one-piece. Casting is the most common method and is a fairly basic concept. It basically involves getting molten aluminum inside of a mold to form a wheel. Below is a description of the ways to cast a wheel.
This is the most basic method of pouring molten aluminum into a mold using the earth’s gravity to fill the mold. Gravity casting is a good way for casting designs that are more visual or when reducing weight is not a primary concern. Since using the earth’s gravity is essential, you will likely find air pockets in the aluminum which could eventually lead to stress cracks and pitting. Gravity cast wheels also will have a higher weight to achieve the required strength.
Low-Pressure casting uses positive pressure to move the molten aluminum into the mold quicker and get a finished product that has improved mechanical properties over a gravity cast wheel. There are also high-pressure cast wheels on the market, which require special equipment to produce. The high-pressure casting will yield a lighter and stronger wheel as compared to the low-pressure cast.
This is a new process of casting where the mold is tilted to almost 90 degrees and then the molten aluminum is poured and the mold moves back to its original position. This process minimizes the bubbling effect of aluminum and reduces air pockets. Due to the high cost of producing such a cast, they are not widely produced.
FORGED or SEMI-SOLID FORGED
Forging is the method of forcing a solid billet of aluminum between the forging dies under an extreme amount of pressure, which is usually around 8000 to 10000 tons. After being put under that pressure, the aluminum is already in the shape of a wheel, even before it’s machined down to the finished product. When it becomes finished it is very dense, strong, and very light.
Semi-solid forging is the process of heating a billet of alloy to an almost liquid state and then the aluminum is forced into a mold at a high rate. The finished product offers mechanical properties that are similar to the forged wheel without the costs of production. Currently only SSR in Japan is licensed to conduct this sort of casting wheels.
Multi-piece wheels are usually comprised of two or three parts assembled together to produce the wheel. The rim sections for the three-piece are spun forge or roll formed from blocks of aluminum. Three-piece rim sections usually offer the ability to custom-tailor wheels for special applications that otherwise would not be available from a one or two-piece set. The rim sections are bolted to the center and normally a sealant will be applied at the assembly area to seal the wheel.
This type of construction was originally designed for race cars in the early 1970s and have been used on cars ever since. The benefit of the three-piece wheels was that in the event you damage a rim section, you could replace that section rather than the entire wheel. Multi-piece wheels can use as many various methods of manufacturing the center design, cast, and forged. Centers can be cast like a single-piece with the various details, textures, and shapes.
Lately, forged have been manufactured by taking a piece of forged disk and having a CNC machine remove sections to create the wheel’s styles. This way is not the same as forging the center disk into shape, since the forged disks are cut into various designs. Three-piece wheels are most popular in the 18-inch and larger wheels with widths as large as 13 inches.
The two-piece design does not offer as many customizations as the three-piece wheel sets do, but they are just as common in the marketplace. Some have the center bolted into a cast rim section and other manufacturers press centers into spun rim sections and weld them together. On the high-end of the two-piece wheel market, the wheels will have forged rims and centers. Since they are not sold at a high volume because of production costs, they tend to be expensive.
BIGGER IS BETTER
Since man invented the first wheel ages ago, there has been the male impulse to have the biggest and the best of anyone out there. With the inception of the custom 20-inch wheels in the 1990s, the craze has led custom wheel manufacturers to saturate the market with high quality custom wheels and tires. The evidence of that fact is there, with manufacturers constantly trying to one-up each other by releasing not only 20 inch wheels, but also 22, 25, 26, and even 30 inch wheels.
THINK OUTSIDE THE BOX
The practical mind thinks that such big wheels can only belong to giant trucks and SUVs. Fortunately, those that think outside the box have found ways to stylishly fit these wheels on their mid-size sedans and even compacts. But there is a method to their madness. The biggest thing to figure out is how to fit larger diameter wheels on any vehicle. The key is the use of ultra-low profile tires. They allow a bigger wheel to fit since it tucks into the fender-wells and avoids interfering with the fender lips and suspension components. The ultra-low profile tires are the state of the art when it comes to tire technology. Their short sidewalls are capable of supporting the weight of the heavier vehicles and they absorb the shock of road hazards and irregularities you may encounter while driving.
UPSIZING IS AN EASY UPGRADE
Most cars in today’s industry are capable of rolling on 22s. The strides taken by manufacturers have allowed the consumer a wider array of not only custom designs, but sizes as well. Dealers now are offering custom wheel packages that include larger wheels. Aftermarket wheel manufacturers are seeing a boom in demand for their products as the craze has hit the streets.
Tips for the First Time Wheels Buyer
DO I NEED TO ROLL MY FENDERS IF I LOWER MY CAR?
Although sometimes tire packages may require the fender to be rolled to prevent rubbing, most do not. It is mostly preference; some prefer to roll the fender for the added protection while some deem it not worthwhile.
IF I GET WHEELS, WILL I NEED AN ALIGNMENT?
It is strongly recommended that the vehicle be aligned after installation. A proper alignment will prevent your tires from wearing unevenly. In addition, make sure that you receive your stock wheels, tires, and lug nuts back just in case anything happens to your new wheels or tires.
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