Wheel FAQ Guide

We recieve questions about our wheels and wheels in general all the time. Here are some faqs about alloy wheels that may help the consumer purchase their wheels.
How are wheels made?
In order from worst to best:
1. Sand Cast. This is the oldes method around, normally produces a heavy wheel.
2. Gravity Cast. An old method, but if it is 17" or under not bad. Typically heavy, but factories that have been using this method for a long time seem to have perfected it. Over 17" the defect rate goes up.
3. Low Pressure Cast. This is the preferred method for a majority of wheels today up to 30". Fairly efficient system. 95% of OE wheels are built this way.
4. Counter Pressure Cast. Slightly better than LPC (#3), can produce some weight savings.
5. Semi Solid Forged.Pretty good method, the brand SSR uses this.
5. Spun Cast. High dollar, but can produce a very light wheel. OE Corvette Z06 wheels were built this way.
6. Forged or Rotary forged. Probably the best method around, Centerline produces this method.
All of the above are or can be effected by operator experience. You can have a monkey operating a forged wheel machine and end up with a crummy wheel while a very experience manufacturer can produce a good wheel with gravity casting. We produce our wheels with LPC as we can produce 17x9" wheels that weigh 20lbs.
Finish:
Below are some of the finishes on the market today with some brief gements:
1. Polished. This is typically a wheel that has been high buffed to a shine that has no clear coat protectant. Pros are they are shinny when kept clean, and sometimes save weight due to no added materials on the face. Cons -- you have to keep them clean with an aftermarket cleaner. Sometimes people will try and clearcoat them, but this sometimes will make them appear more dull or make them appear milky or yellow. The better the casting and better quality AL will make a more shiny wheel.
2. Powdercoat. A very popular method. Basically an electrostatic method of applying this make it very tough and avoids runs or imperfections.
3. Paint. An old method that is now being revisited due to advances in paint technology. Painted wheels tend to have more depth to them, but can also have imperfections if the paint process is not clean and up to date. We just switched from powdercoat to paint as our new German technology paint line produced superior results as far as finish when gepared to powdercoat.
4. VSP. Vacuum Sputter Coating. Very similar to Powdercoating. Many gepanies are using this as an alternative to chrome. If done right it is a very good process. The problem is most manufacturers have not mastered this process.
5. Chrome. Everyone loves chrome! "Triple Dip", kinda a misconception. A 5000' overview of chrome platting. Wheels are polished, then copper platted, low nickel, high nickel then chrome. What you really see that is shinny is the high nickel. The chrome is the top layer that is hard. A easy way to think of this is if you take the clearcoat off your car your paint would not look as glossy or shinny and would flake, you take the chrome off your wheel you are going have the same results, high nickel flake!
6. Andodize. Very rare but also very tough finish. Has normally a metalic look to it. Often seen in colors such as blue, red, purple and sometimes silver or black.

Offset.
Imagine ifa wheel was sitting upright, like it was on your car. If you were to look at it from the top you could divide the wheel in two even halfs. The face half, whichfaces outward and thebackside half which faces the inside of your car.If you were to draw a line to divide the two halfs that would be your CENTERLINE. The distancefrom the centerlineto where the mounting pad is is called the offset. The mounting pad is the flat area or pad that mats to the brake hat or hub. The offset is measured in Millimeters. There are 25.4 mm in one inch.
So if your mounting pad is one inch awayfrom the centerline of the wheel it has a +25.4mm offset. That is ifthe one inch is to theface side of the wheel. If the one inch is to the backside of the wheel then it is a -25.4mm offset.

Backspace
This is the measurement from the mounting pad to the very backside of the wheel. This is normally calculated in inches.

The million dollar question that everyone seems to have a hard time understanding. How are backside and offset correlated? This is best defined by an example:
A 17x9 wheel is not 9 inches wide overall. It is actually closer to 10 inches. The 9 inches is a measurement from bead to bead on the wheel cross section. If you were to measure from one edge to the other edge it would be very close to 10 inches. The reason is the flange on each side is normally around .45 to .5". Thus, in our example our 17x9 inch wheel is 10 inches from side to side. The centerline would make each even half 5 inches. If you were to have a +25mm offset the mounting pad is about 1 inch to the face of the wheel from the centerline. Hence your backspace would be your backside 5" half and your 1" offset to total you a 6" backspace.

Bolt Pattern
Often given in metric mm or inches. ie, 5x4.5 is the same as 5x114.3. This is the distance from one lug hole to the farthest lughole on the opposing side.

Centerbore
This is measure in mm. This is the width of the centerhole of the wheel which goes over the hub of your car. Some vehicles are hubcentric, meaning that to attain the best ride you need the centerbore to be specific to your vehicle. Often wheels are made lugcentric, meaning that the wheels are built to use 60 degree tappered acorn lugs or shanked lugs to try and make up for not being hubcentric.

I hope this helps some, I wrote it real late at night!!