Wheels (FAQ)

From SCION-TECH : The Scion Resource : tC, xA, xB, xD

Contents 1 Also See 2 G37 Specific Questions 2.1 Scion xA Specific 2.2 Scion xB Specific 2.3 Scion xD Specific 2.4 Scion tC Specific 3 General 3.1 Wheel and Tire Calculators 3.2 Offset 3.3 Bolt Patterns 3.4 Plus Sizing 3.5 Wheel Care 3.6 Centerbore 3.7 Torque 3.8 Alloy vs. Steel 3.9 Hardware 4 Wheel Manufacturing 4.1 Wheel Construction 4.2 Gravity Casting 4.3 Low Pressure Casting 4.4 Tilt Die Casting 4.5 Forged 4.6 Multi Piece Wheels 4.7 Two-Piece Wheels

[edit] Also See

• Tires (FAQ)
• Wheel and Tire Definitions

[edit] G37 Specific Questions

[edit] Scion xA Specific

Factory Wheel SIzes (xA)

[edit] Scion xB Specific

Factory Wheel SIzes (xB)

[edit] Scion xD Specific

Factory Wheel SIzes (xD)

[edit] Scion tC Specific

Factory Wheel SIzes (tC)

[edit] General

[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

• Discount Tire size calculator
• Discount Tire Wheel FAQ
• Mark Sink rim offset calculator
• Mark Sink tire size calculator

[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:'

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

Plus 2:'

1. Increase section width by 20mm
2. Decrease aspect ratio by 20 points
3. 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.