Sponsored by The Tire Rack

[Rudy@tirerack]

This thread is to provide basic tech information for wheels.

Performance benefits:
While many people choose alloy wheels for their beauty, there are equally important performance benefits to be derived including...

Reduced Unsprung Weight Compared to Steel Wheels
This is one of the most critical factors affecting a vehicle's road holding ability. Unsprung weight is that portion of a vehicle that is not supported by the suspension (i.e. wheels, tires and brakes) and therefore most susceptible to road shock and cornering forces. By reducing unsprung weight, alloy wheels provide more precise steering input and improved "turning in" characteristics.

Improved Acceleration and Braking
By reducing the weight of the vehicle's rotational mass, alloy wheels provide more responsive acceleration and braking.

Added Rigidity
The added strength of a quality alloy wheel can significantly reduce wheel/tire deflection in cornering. This is particularly critical with an automobile equipped with high performance tires where lateral forces may approach 1.0g.

Increased Brake Cooling
The metals in alloy wheels are excellent conductors of heat - improving heat dissipation from the brakes - reducing risk of brake fade under demanding conditions. Additionally, alloy wheels can be designed to allow more cooling air to flow over the brakes.

What determines quality?
The Tire Rack’s quality standard for wheels is very high and the manufacturers that we represent in this market understand that we constantly monitor products to ensure that quality products are sold to our customers. But what determines quality?

Manufacturing Process
Manufacturing processes and levels of testing are critical to a wheel's structural integrity. (Read more in "Wheel Construction.") International quality standards such as ISO9001, QS9000, TUV of Germany or VIA of Japan, establish important production and quality standards that manufacturers must follow. In addition, dimensional tolerances based on strict, original equipment market standards versus the more “casual” standards allowed for many aftermarket products should be met. Even durability standards for finish are different between the original equipment market and the aftermarket.

Proper Fit
An accurate fitment is the difference between good, better and best. Critical wheel dimensions such as width, diameter, offset, center bore, brake clearance, as well as load factor and lug hardware are the basics when it comes to properly fitting aftermarket wheels. Installation also requires a high level of sophistication. Many new vehicles are available with features such as ABS, traction control and other features that create a more difficult environment for installing aftermarket wheels. Stability control systems, run-flat tires, large high performance brake systems and staggered wheel and tire sizes are also factors to be considered when establishing accurate fitments. Wheel manufacturers with product design, research and development teams work to determine proper fitment as part of the manufacturing process.

Protective Finish
The type and quality of protective finish on your wheel (as well as proper maintenance) will determine how your wheels look years from now. Check for finish warranties backed by manufacturers with outstanding reputations for quality.

Reputation and Heritage
The reputation of a manufacturer is a strong indicator of quality since it is quality upon which a distinguished reputation is built. It takes time to build a positive reputation and a commitment to maintain it is important. And know a wheel company's roots. Many wheel manufacturers first established themselves in the motorsports arena and apply that technological and philosophical foundation to their production of wheels for use on the street.

The Tire Rack's Commitment to Quality
The Tire Rack constantly reviews wheel data from new vehicles to be sure that we are aware of the original equipment sizes and packages offered. We physically inspect many of today’s new vehicles and often supply technical data to some of the manufacturers outside the U.S. that may not have access to certain vehicles in our market. For many wheels that we import or represent, we specify certain dimensions that we require to ensure wheel fit and maintain our high quality standards.

Offset:


The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types.

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.

Torqueing lug hardware:
Proper installation requires that the wheel lug torque be set to the recommended specification for your vehicle. These torque specifications can be found in your vehicle’s shop manual or obtained from your vehicle dealer. Finish tightening the lugs down with an accurate torque wrench. Use a crisscross sequence (shown below) until they have reached their proper torque value. Be careful because if you over torque a wheel, you can strip a lug nut, stretch or break a wheel stud, and cause the wheel, brake rotor and/or brake drum to distort.

NOTE: When installing new wheels you should re-torque them after traveling the first 50 to 100 miles. This is necessary because as the wheels are “breaking in” they may compress slightly allowing their lugs to lose some of their torque. Simply repeat the same torque procedure listed above.