Wheels (FAQ)

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From The Infiniti G37 Information Resource

(Redirected from Centerbore)

[edit] Also See

[edit] G37 Specific Questions

[edit] What offsets for rims will fit my G37?

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Front

Rear

[edit] Factory Wheel Sizes

For more information: G37 OEM Wheel Specifications

[edit] Lug Nuts

Stock lug nuts are chrome acorn style M12 x 1.25 with a 21mm head

[edit] Lug Torque

The Nissan Factory Service Manual suggest 73-93ft-lbs (foot pounds) for the OEM wheel lug torque.

[edit] OEM Bolt Pattern

The G37 wheel bolt pattern is 5/114.3

"5" indicates the number of holes in the wheel for the bolts to enter and mount the wheel onto the car.

"114.3" indicates the diameter of the bolt circle measured in millimeters (or inches). A special tool is usually required to measure bolt circle for a 5 bolt pattern. Imagine a circle running through the centers of each bolt hole. You would measure from the center of one bolt hole to the imaginary circle that lays between the opposite two bolt holes. See the following diagram:

[edit] Wheel Stud

Image:Wheels stud.jpg

OEM Wheel Stud

Length40mm

[edit] General

Offset

Bolt Pattern

[edit] Wheel and Tire Calculators

These links answer alot of the more common questions concerning wheels and tires. This is from Discount tire website FAQ

[edit] Offset

The offset of a wheel is the distance from the mounting surface of the wheel to the true centerline of the rim. A positive offset means the mounting surface of the wheel is positioned in front of the true centerline of the rim / tire assembly. This in effect brings the tire in to the fender well more. Conversely, a negative offset means the mounting surface of the wheel is behind the true centerline of the rim / tire assembly. This will cause the tire to stick out away from the vehicle.

To compare the effects of changing the offset and width of your wheels use the Wheel Offset Calculator

Zero Offset

The hub mounting surface is even with the centerline of the wheel.

Positive

The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.

Negative

The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset.

If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly. We have test fitted thousands of different vehicles for proper fitment. Our extensive database allows our sales staff to offer you the perfect fit for your vehicle.

[edit] Bolt Patterns

Each wheel has a different bolt pattern, and some wheels even have 2 different bolt patterns which allow it to be mounted on a wider range of vehicles.

Most Bolt Patterns are represented in the following manner: 4/100

The "4" indicates the number of holes in the wheel for the bolts to enter and mount the wheel onto the car.
The "100" indicates the diameter of the bolt circle measured in millimeters or inches. 4 & 6 bolt wheels are measured from the center of one bolt hole to the center of the bolt hole directly across from it. On a 5 bolt pattern, it is a bit trickier to measure without special tools. Imagine a circle running through the centers of each bolt hole. You would measure from the center of one bolt hole to the imaginary circle that lays between the opposite two bolt holes.

[edit] Plus Sizing

Plus sizing your wheel & tire combination was designed to enhance vehicle performance and looks by allowing fitment of larger diameter rims and lower profile tires. The theory is that while making these changes, you keep the overall tire diameter within 3% of the original equipment tires. This is important because larger variances can cause problems with transmission shift points which can decrease fuel mileage. It can also confuse braking system computers which can even lead to brake failure.

Here's the rule of thumb for "plus sizing":

Plus 1:'

Increase section width by 10mm
Decrease aspect ratio by 10 points
Increase rim diameter by 1 inch

Plus 2:'

Increase section width by 20mm
Decrease aspect ratio by 20 points
Increase rim diameter by 2 inches.

This is not exact, but it will usually get you in the right ballpark. We always recommend consulting with the people you are purchasing the wheels and tires from to ensure fitment.

[edit] Wheel Care

It is important to keep your wheels clean at all times. Your brakes will cause the wheels to heat up, and this heat in turn can cause any dirt or brake dust to cook in to the clear coat. If this happens, there's not a lot you can do besides having the wheels refinished. Protect your investment and keep your wheels clean!

Below are some simple instructions on how take care of your wheels:

Do not use household cleaners or other detergents to clean your wheels. The best wheel cleaning solution is a mild soap and water solution (what ever you would trust on the paint of your car). Clean with a soft, un-abrasive cloth. Only on polished wheels can you use aluminum wheel polish. If you use this polish on chrome, painted, or clear coated wheels, you will only scratch or dull the finish.
Do not use steam cleaners in automatic car washes.
Do not use any tire cleaners on your wheels.
Clean wheels when they are cool. Heat can effect the soap, causing it to dry on the wheel and become difficult to rinse off.
Clean one wheel at a time. This also prevents the soap from drying on to the wheel.
After the wheels are clean and dry, apply a coat of soft paste style wax to them. This will create a moisture barrier and help ensure the finish lasts as long as possible.

[edit] Centerbore

This relates to the center hole in the wheel that centers the wheel on the hub of the car. Since most wheels are mass produced, they have a large center bore to accommodate several different vehicles. If this is the case, it is recommended that you use a hub ring. Hub rings are hard plastic or metal ring that fits between the wheel and the vehicle. This centers the wheel perfectly on the hub ensuring that there is no run out when the wheel is installed on to the vehicle. Without hub rings it is possible to get vibrations even if the wheel / tire assembly is perfectly balanced.

[edit] Torque

All alloy wheels should be installed using a torque wrench. This ensures that the wheels are not too tight or too loose. Check your vehicle's manual for correct settings. When you install wheels for the first time, you should re-torque wheels after about 100km to 150km (60 to 90 miles).

[edit] Alloy vs. Steel

The main differences between alloy and steel wheels lie in their durability and strength. Most high-performance wheels are made of an alloy and composed of aluminum, and other metallic substances. By using alloy wheels, you not only improve the looks of your vehicle but also the performance. The extra strength provides longevity as well as effecting tire wear in a positive manner. The weight reduction will improve steering response and handling, as well as help improve acceleration and braking.

[edit] Hardware

The hardware holding your wheels to your car is an often overlooked step when installing new rims. Most aftermarket wheels require different wheel nuts / bolts than what was used on the original equipment wheels. Wheel nuts and bolts have many different seats (where the nut touches the wheel). The 3 most common are acorn seat (conical), ball seat (radius), and mag shank seat. These differences along with different lengths and diameters makes hardware very confusing. Always check with the people who supplied your wheels for the correct mounting hardware before trying to install them on your vehicle..

[edit] Wheel Manufacturing

[edit] Wheel Construction

There is a good variety of ways of constructing wheels. Most alloy wheels are made in either one, two or three piece construction types. One piece is just what it says, a wheel made in a mold as a single piece. Two piece wheels are made of two separate pieces (center and barrel) that are usually welded or bolted together. Three piece wheels are made of three separate pieces. They have a center, and inside rim half, and an outside rim half. They are bolted together using the highest quality fasteners.

Manufacturing method is very important in the overall quality and performance of a wheel.

[edit] 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 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 or has various air pockets, which may increase the chances of pitting or stress cracks. In addition, gravity cast wheels will have a higher weight to achieve the required strength.

[edit] Low Pressure Casting

Low pressure casting uses positive pressure to move the molten aluminum into th emold quicker and achieve a finished product that has improved mechanical properties (more dense) over a gravity cast wheel. Some companies offer wheels that are produced under a higher pressure casting which involves special casting equipment, which in turn creates a wheel that is lighter and stronger than a low pressure comparison.

[edit] Tilt Die Casting

Tild die casting is a new process of casting wheels where the mold is tilted to a near 90 degrees and then 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. To make it simpler... it's like pouring beer into a glass. If you dump it in itll create foam (air pockets) but if you tilt the cup it will have a lot less bubbles or foam. Due to high cost of this type of molds, few factories, such as Merit Alloy/MRR Design, utilize this state of the art technology to produce wheels. Other brands, which use this technology, include,, Manaray,, Venerdi,, and many more.

[edit] Forged

Forging is the process of forcing a solid billet of aluminum between the forging dies under an extreme amount of pressure, usually 8,000 to 10,000 tons. After being put under pressure, the aluminum has a shape of a wheel before it's machined down in detail. The results are a finished product that is very dense, very strong and therefore can be very light. There are few companies that still offer forged single piece wheels such as APP, Centerline, Forgeline, Raceline, and Weld.

Semi-solid forging (SSF) is a process that heats a billet of special alloy to an almost liquid state and then the aluminum is forced into a mold at a very high rate. The finished product offers mechanical properties very similar to a forged wheel without the high production and tooling costs of a forged wheel. Currently only SSR (Speed Start Racing) from Japan is licensed to used this process for the production of wheels.

[edit] Multi Piece Wheels

Multi-piece wheels are usually two or three parts assembled together to produce a finished wheel. The rim sections for three-piece wheels are either roll formed or spun forged from blocks of aluminum. Generally, three-piece 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 assembley area to seal the wheel.

This type of three-piece construction was originally developed for racing in the early 1970s and has been used on cars ever since. The original benefit of three-piece wheels was, in the event that you damage part of a rim section, the rim section could be replaced without having to replace the whole wheel. Multi-piece wheels can use many different methods of manufacturing the center design, cast and forged. Centers can be cast like single-piece wheels with various details, contours and shapes. Brands like 5-Zigen, Brabus, Maya, Maido, Lowenhart, Volk Racing, Racing Hart, and Lorinser use cast centers.

Forged, lately, have been manufactured by taking a piece of forged disk and having a CNC machine cut away at sections to create the style of wheels. This process is not the same as forging the center disk into shape, since the forged disks are cut into various designs. The three-piece wheels are most popular in teh 18-inch and larger diameters with widths as large as 13 inches in some applications.

[edit] Two-Piece Wheels

The two-piece wheel design does not offer as wide a range of custom-tailor applications that a three-piece wheel allows, however they are common in the market. Some two-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 two-piece wheel to replace the previous three-piece street wheel, they used the special rim-rolling technology (orginally 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 two-piece wheel market, you can find wheels using forged rims and forged centers. Since these are only sold in small volumes, 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.

[edit] Wheel and Tire Definitions

Air Pressure: the measure of the force exterted by the air inside a tire, measured in pounds per square inch (psi) or kiloPascals (kPa)
Alignment: refers to the correct angle settings of suspension components - the 3 alignment settings are caster, camber and toe.
Aspect Ratio: the relationship between a tire's section height and its section width. It is calculated by dividing the section height by the section width. When the section height is half of the section width, the aspect ration is 50. In a tire size description, it would be the 50 in P195/50R15. It is also called the tire's profile or the series.
Asymmetric: tires that have differing tread patterns on each half of the tire
Balance: equal distribution of the weight of a tire and wheel. If a tire & wheel is not balanced it can lead to vibrations or uneven wear. For balancing, weights are attached to the wheel to compensate for uneven weight distribution.
Backspacing: also called rearspacing, it is the distance from the mounting pad to the back edge of the rim. This is different than wheel offset.
Bead: the part of the tire in contact with the wheel flange. It is made of high tensile steel wires shaped to fit the rim and hold the tire on the wheel. The steel wires are wrapped in woven fabric and held in place by the plies.
Bead Seat: the edge of the rim that creates a seal between the tire bead and the wheel
Belted Bias Tires: tires constructed similar to bias tires, but with reinforcing belts between the casing plies and the tread.
Belts: rubber coated cords located between the plies and the tread. They help reinforce the tread, as well as help the tire keep its shape against such forces as: tire inflation pressure, centrifugal force, cornering and braking. These cords are made from such materials as steel, fiberglass, radon, nylon, polyester or other material.
Bias Tire: a tire that is constructed with plies laid out in alternating directions in angles about 30-40 degrees to the center line of the tire. The plies form a criss-cross pattern.
Bolt Pattern: the arrangement of the bolt holes on a wheel. A 4 bolt wheel with 100mm between opposite bolt holes would be written as 4/100. Some wheels have more than one bolt pattern on the same wheel to accomodate multiple fitments.
Camber: the angle of the centerline of a tire and wheel relative to completely vertical.
Cast: wheels that are made from liquid metal being poured into a mold. Low pressure casting involves pouring into a mold, while counter pressure casting involves sucking the metal into the mold like a vaccuum. The counter pressure technique reduces impurities making the wheel much stronger than a low pressure cast rim.
Caster: the angle between the vehicle's steering pivot axis and completely vertical.
Centerbore: the center hole in the wheel that centers the wheel on the hub of the car. Since most wheels are mass produced, they have a large center bore to accommodate several different vehicles. If this is the case, it is recommended that you use a hub ring. Hub rings are hard plastic or metal ring that fits between the wheel and the vehicle. This centers the wheel perfectly on the hub ensuring that there is no run out when the wheel is installed on to the vehicle. Without hub rings it is possible to get vibrations even if the wheel / tire assembly is perfectly balanced.
Chafer: abrasion resistant rubber coated material to help prevent the tire's beads from rim damage and chafing.
Cold Inflation Pressure: the measure of air pressure of a tire that is not warm from driving (less than 1 mile or standing for at least 3 hours)
Compound: the materials used in the construction of the tire's rubber. The main materials used are rubber, carbon black, plasticizers, curing materials and ozone retardants. Different compounding formulas are used to achieve different tire characteristics such as: heat resistance, increased traction, increased treadwear, cut resistance, cold resistance, etc.
Cord: strands of nylon, rayon, polyester, steel or fiberglass that make up the plies & belts of the tire. The strength of a tire & its load carrying capacity is determined by the strength of the cords.
Crown: the center section of the tire's tread
Curb Guard: extra rubber running around the sidewall of a tire. It is there to protect the side of the tire and the wheel face from any damage that may come as a result of hitting a curb.
DOT: stands for Department of Transportation. The 10 digit code appearing after the DOT designation gives information such as the week and year the tire was produced, as well as the manufacturer, plant, tire line, and size.
Footprint: the area of the loaded tire's tread that is in contact with the road. This is also called the contact patch.
Forged: Considered to be the best wheel manufacturing technique, forging allows for the compression of an aluminum billet (one solid piece of aluminum) into an aluminum wheel using over 13 million pounds of pressure combined with heat. This produces a wheel that is both stronger and lighter then your standard aluminum wheel.
Grooves: the space between two tread ribs of a tire
Hub Centric: a wheel with a centerbore made to match up with a vehicle's hub diameter.
Hub Centric Rings (Hubrings): hard plastic or aluminum rings mounted on a vehicle's hub before the wheel. They ensure the wheel is perfectly centered on the vehicle's hub. Without hub rings, there is a possibility of getting a vibration even if the wheel & tire assembly is perfectly balanced.
Hydroplaning: when a tire loses traction as a result of water on the road. The water accumulates under the tire's footprint and causes the tire to lift from the road surface. Vehicle speed, tread pattern and water depth all affect hydroplaning.
Load Index: a number used to represent the maximum weight a tire can support. The index number corresponds to the actual load carrying capacity. Truck tires use a different system incorporating letter codes to establish a Ply Rating. >More Info
M+S: a sidewall marking indicating that the tire is approved for Mud & Snow use. This approval is made by the RMA (Rubber Manufacturers Association).
Mixing Tires: combining different tire sizes or tire models. This is not recommended as not all 4 tires will respond the same and it may cause unpredictable handling. Some performance vehicles do come stock with different front and rear tire sizes.
Mounting: installing tires onto wheels
Offset: The offset of a wheel is the distance from the mounting surface of the wheel to the true centerline of the rim. A positive offset means the mounting surface of the wheel is positioned in front of the true centerline of the rim / tire assembly. This in effect brings the tire in to the fender well more. Conversely, a negative offset means the mounting surface of the wheel is behind the true centerline of the rim / tire assembly. This will cause the tire to stick out away from the vehicle.
Overinflation: when a tire is inflated more than the recommended vehicle air pressure. This might be done for better performance but has negative consequences including: a less comfortable ride, damage to the tires and stress on the suspension.
P-Metric System: a system for specifying tire sizes using the treadwidth (millimeters), the aspect ratio, type or tire construction and the rim diameter (inches). The sizes are written as such: P195/50R15
Plus Sizing: changing from the original stock tire size of your vehicle. Plus sizing your wheel & tire combination was designed to enhance vehicle performance and looks by allowing fitment of larger diameter rims and lower profile tires. The theory is that while making these changes, you keep the overall tire diameter within 3% of the original equipment tires. This is important because larger variances can cause problems with transmission shift points which can decrease fuel mileage. It can also confuse braking system computers which can even lead to brake failure.
Ply: layers of cord fabric that give a tire its strength. They are situated between the tire tread and the innerliner, and they run from bead to bead. These cords are rubber coated.
Profile: refer to aspect ratio.
PSI: the most common measurement unit for tire pressure. It stands for pounds per square inch and it measures the force exterted by the air inside a tire.
Radial Tire: tires built with plies running perpendicular (90 degrees) across the crown of the tire. To strengthen the tread, these tires require belt plies going circumferentially around the tire.
Retreading: applying new tread to a used tire casing. This practice is common among medium & heavy trucks.
Ribs: rubber sections of the tread that run around the circumference of the tire
Rim Width: the measurement between the flanges of a rim
Rotation: moving a vehicle's tires from left to right and from front to rear. This is done in a set pattern and should be done periodically. Its purpose is to prevent uneven tire wear and to extend treadlife.
Section Width: the distance between the sidewalls at their widest point of an inflated tire not under load.
Series: refer to aspect ratio.
Shoulder: the outer edge of the tire tread where it meets the sidewall
Sidewall: the side portion of a tire between the tread and the bead. >More Info
Sipes: small slits in a tire's tread that help push water away from the crown of the tire for improved wet traction. They also provide biting edges for ice and snow traction.
Speed Rating: a letter that identifies a tire's high speed durability. A tire's capabilities are tested at preset speeds and the results of these tests determine the tire's speed rating. Speed Ratings include: Q, S, T, U, H, V, Z, W, Y >More Info
Tire Placard: a label on a vehicle that identifies the vehicle's stock tire size and its recommended tire air pressure. This label is often found on the inside of the vehicle's door.
Toe: the difference between the distance between the front left & right tire and the distance between the rear left & right tire. Toe-In means that the front of the tires are closer together than the rear. Toe-Out means that the rear of the tires are closer together than the front.
Tread Blocks: individual sections of the tread separated by lateral grooves
Tread Depth: the distance from the top of the tread to the grooves in a tire. This measurement is taken at the centerline of a tire and is measured in thiry-secondths of an inch.
Tread Pattern: the arrangment of grooves, blocks, sipes and channels on the tread.
Tread Shaving: shaving some of the tread from a tire for optimal performance and durability in racing applications.
Tread Wear: also called the tread life, it is the measure of how long a tire lasts. It is measured in miles or kilometers.
Tread Wear Indicators: narrow rubber bars built into the tread grooves that define the tire's legal wear out point. Also called the wear bars, they are even with the tread when 2/32" of tread is left and then the tires are ready to be replaced. >More Info
Treadwidth: the width of a tire tread, normally measured in millimeters. In 195/50R15 the treadwidth is 195mm.
Underinflation: a tire with less than the recommended air pressure for a given load. This may lead to tire rollover and deflection.
UTQG: The Uniform Tire Quality Grading rating is a quality rating system developed by the American Department of Transportation. It is designed to tell consumers the relative performance of passenger tires (but does not apply to winter tires). >More Info

Wheel Weights : weights attached to a wheel to balance a tire & wheel. The weights can be on the inside or outside of the wheel and can be clipped, taped or self-adhered to the wheel.

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