Going back to the 50′s and early 60′s, the Aftermarket Wheel Industry was born because of the desire of car guys that wanted something other than stock painted wheels in stock sizes. These cars guys wanted chrome wheels and they wanted them wider so they could use bigger tires. At that time, the OEM’s didn’t offer aluminum wheels. As a result the stud length was shorter on the vehicles. The average stud length was about 3/4″ to 7/8″. This was adequate for steel wheels and there were no thread engagement issues. Then in the early 60′s, the Aftermarket Wheel Industry started offering aluminum alloy wheels. The developers of these wheels solved the thread engagement problem by coming up with the Mag Type lug nut. Since the mounting pad thickness was about the same thickness as the stud length on the vehicles, which left little or no threads on the stud to attach a standard conical seat lug nut, they came up with a lug nut that had a shank that went into the wheel lug hole enough to accomplish proper thread engagement (see illustration). This system was adequate but left a lot to be desired. In order to assure that the wheel was attached to the vehicle with good alignment and acceptable runout, the diameter of the lug hole had to be drilled with a minimum of clearance for the lug nut. After the vehicle was driven enough to heat up the brakes and wheels, the aluminum wheel expanded, thus shrinking the diameter of the lug nut hole. It was then very difficult to remove the lug nuts when the wheel was hot, in order to change a flat tire or what ever.

Now moving forward in time, the OEM’s began offering aluminum alloy wheels on new vehicles. They determined that the use of Mag Type lug nuts was not the best system. They began to offer their aluminum wheels with conical seat lug nuts. They did however lengthen the studs on the vehicles that were offered with aluminum wheels so there was adequate thread engagement. This prompted the Aftermarket Industry to adjust their offering so they could keep up with the OEM’s. In the late 80′s, the Aftermarket Industry began drilling their lug holes with a conical seat instead of the Mag Type lug hole. It was then discovered that the use of a standard lug nut (Acorn Type) was causing problems with the seating area of the wheel. Steel inserts was a solution, but it was soon discovered that the OEM’s were using a Bulged Type lug nut which eliminated the problem with the seating area. So the Aftermarket lug nut manufacturers started offering Bulged Type lug nuts. At that point it seemed that all was well in the Aftermarket Wheel Industry. Not so.

The problem of thread engagement became an issue when a conversion from steel to alloy wheels was made on vehicles that had short studs and were never intended to have alloy wheels. The Aftermarket again responded by developing a Bulged Type lug nut with an extension that would go into the lug hole enough so that proper thread engagement could be accomplished. This lug nut was called the ET (extended thread). Combined with the bulged seat area, the extended thread provides the best attachment that is currently offered.

I have recently observed another problem. In my illustration I show examples of wheels with mounting pad thicknesses from .390″(10mm) to .630″(16mm). I do not recommend a mounting pad thickness to be greater than .390″(10mm). I have done extensive testing on wheels produced in China since 1993 using a .390″(10mm) mounting pad thickness. I have sold in excess of 750,000 wheels and never experienced any failures. Using a Std. Bulged Type lug nut in a wheel with a .390″(10mm) pad thickness on a vehicle with short studs (.800″) (see illustration) is still under the minimum thread engagement recommendation of SAE. And using an ET Bulged Type lug nut in a wheel with a .630″(16mm) pad thickness on a vehicle with short studs (.800″) (again see illustration) is also under the minimum thread engagement recommendation of SAE. In my opinion, ET lug nuts should be used on all aluminum wheels. In summary, what does an ET Type lug nut do? It provides a method to assure proper thread engagement. What is proper thread engagement? Proper thread engagement is defined as engaging the threads onto the bolt or stud by at least the diameter of the bolt or stud. Prior to mounting a wheel on a vehicle, the length of the stud should be checked against the thickness of the mounting pad below the bottom of the conical or spherical seat. Another way to check is to mount the wheel and check how many turns the fastener makes before it reaches the seating area. An example is if using a ½”-20 nut, then there should be at least 10 complete turns.

Prior to retiring, I owned and operated WheelTech International Corp. I’ve been in the wheel industry for 40 years. I started in the steel wheel business and evolved into aluminum wheels. I still like steel wheels but simple chrome plated alloys are my choice. Back in 1969 I worked with another company and developed the first Smoothie style steel wheel. I was in the metal stamping business then and built the tooling and stamped the centers. I later designed the Steel Mod wheel in 1979. After that I was hooked. I ate, breathed and slept wheels.

In 1981 I formed a small wheel company called Cal/Master. I specialized in VW and FWD steel wheels. In 1987 I sold Cal/Master to Progressive Wheel in Riverside California. That’s when I was introduced to aluminum wheels. I spent the next 4 years learning the art of manufacturing aluminum wheels, both one piece and two piece. I found I had a particular flair for designing, so I dove head first into learning everything I could about designing, engineering, testing and manufacturing.

In 1990, I fell into an opportunity that set the course for the rest of my career. I was offered a project to design the wheels for a new company being formed in China. I was part of a group that built a complete turn key aluminum wheel manufacturing factory. This factory was the second of what was to become many such factories in China and So. Korea. These factories were built using the latest state-of-the art equipment and technology. Compared to the factories operating in the States at the time, these were light years ahead in technology. The quality was far superior and the costs were much more competitive.

I designed the initial group of wheels for the Chinese factory based on what would sell in the US. After the wheels were tooled and ready for production, the Chinese came to me and asked if I knew where they could sell the wheels. After a long period of contemplation (about 10 seconds) I agreed to give it a whirl. It’s a lot more involved and complicated, but to put it simply, I again fell into a situation that got me a national account that bought and sold a lot of wheels, Sears. This afforded me the opportunity to travel all over Asia (every country but 5 or 6), see many sights and meet many very nice people. I wouldn’t trade those experiences for anything, even a Hot Rod built by Boyd or Chip.

In 2000, I decided to slow down a bit and get back to my favorite hobby and first love, (other than my wife of 44 years and my kids), cars. I started building a 1929 Model A when I was just out of high school, but I joined the Marines and that ended that. My first project was to build a shop at home. So I added a 1000 sq ft shop on my property. Then I found a 1954 Olds Super 88 (that’s what I had in high school). When I started looking for wheels for the Olds, I couldn’t find anything I liked. Everyone either had Torque Thrusts, Cragar SS’s or Billets. I wanted something different. That prompted me to design the TQ Rod Wheel. I wanted a 5 spoke, fairly deep dish and chrome plated. I used the Torque Thrust, the Cragar SS and the Supreme as my inspiration, and the TQ was the result.

I later discovered that the old Slotted Mags were only found at swap meets so I bought an old Indy Mag and used it to design the SLT Muscle Mag. Then I noticed that the Rodders were starting to ask for more lip (I’d go there, but I won’t) so I came up with the RT5 Retro Alloy.

Now I’m retired, and except for writing these TECH Stuff articles, and doing a little technical consulting for the factory, I’m working on my Olds and some honey-do-list items my wife laid on me my second day of retirement. I sold my three Hot Rod Wheel business to some really nice folks in Long Beach, California, Hank and Glenn Feldman. They have been in the wheel business over 30 years and have a real handle on the business and can meet any need you have. They offer tires along with the wheels. They not only sell the TQ, SLT and RT5 but some of the other wheels that I mentioned (that everyone has). If you are tired of seeing the same styles (sometimes I think Torque Thrusts were OEM on Tri-Five Chevys), then check out the TQ, SLT or RT5 now offered by HRH Classic Alloys.

As for me, I’ll never be famous, but I do know wheels. Unlike a couple of really good Hot Rod designers/ builders, turned TV celebrities, turned wheel designers, I’m a wheel engineer/designer turned 65 and retired. I have created a Blog, so if you want to rain on my parade or ask me some technical questions, look me up at WheelProfessor.com, I’d love to share 40 years of experience.

 Here are some examples of modifications that are risky, even dangerous:

 It is pretty tough changing the bolt pattern in a steel wheel.  I think it would be easier to change the brake drums or rotors/axles.  Aluminum wheels can be modified fairly easy.  Caution is advised when considering drilling a new set of lug holes in aluminum wheels.  It is done frequently and there are machines that are built especially for this purpose.  If you choose this type of modification, make sure you use someone who knows what they are doing and has had experience.  One thing that is absolutely not recommended, is putting a truck bolt pattern in a passenger car wheel.  Trucks have a much higher load requirement than passenger cars. 

Straightening and refinishing

There are shops with special equipment to straighten bent wheels.  Steel and formed or forged aluminum are the easiest and least risky.  Steel can be bent and straightened without much fear of fatigue or cracks.  Cast aluminum however is another story.  Most cast aluminum wheels are made from heat treatable alloys.  Some European wheels are made from high silicon alloys that don’t require heat treatment.  The high silicon alloys have more elasticity and can be bent back into their original shape with less chance of fractures or cracks.  Heat treated alloys are not so pliable and can easily crack when not properly done.  Again, knowledge and experience are the keys to success. Refinishing is not much of a problem.  Steel and aluminum painted wheels can be stripped and repainted with no problems.  Steel chrome wheels have to be taken apart and rechromed separately (rim and center).  Chrome plated aluminum wheels are easier than steel because they are already one piece.  Stripping the chrome requires some knowledge because the chrome is stripped chemically, and if not done properly, can damage the aluminum casting.    The big no-no in refinishing aluminum wheels is re-machining the face of a wheel to clean it up and take out nicks and scratches.  Machining the face of the wheel removes metal from the wheel.  This changes the thicknesses of the original design and therefore changes the structural integrity of the wheel.  Enough said. I am not a fan of any type of modification other than refinishing.  Buy them new the way you want them.  If you can’t do that, make sure you do it right and make them safe. 

1.  Style

I’m sure we all have a style in mind that we’ve pictured in our heads that would look cool on our Rod.  The 3 most significant appearance features of a custom ride are the body styling, the paint scheme and the custom wheels.  The wrong wheels on a custom rod is the same as wearing brown shoes with a tuxedo.  Some of us are nostalgia freaks that want the same custom wheels we had on our first car, and then there are those who think billet is cool and others who want a touch of today in their wheel style.  In any event, make sure the wheels you want are available for your particular Rod.

2.  Finish

In an earlier TECH Stuff (#7) we discussed finishes of custom wheels along with their proper care and maintenance.  This is a big consideration.  Painted and chrome wheels require the least maintenance.  Polished aluminum requires the most.  Think about how much time you are willing to or can devote to cleaning your wheels.  Also check out the finishes available for the style of wheel you want.  Steel wheels are available in painted or chrome.  Cast one piece aluminum and forged wheels are available in painted, machined finished, polished and all chrome.  Billet 2 piece wheels are offered in machined or polished only.  Composite (steel rim / aluminum center) only come in all chrome.

3.  Size

After you have made your style choice, check to see the available sizes.  The older styles that are still available are most likely offered in 14″ & 15″.  The newer styles are probably not available in 14″ and the pickens are slim in 15″.  For some reason a lot of the manufactures have skipped the 16″ and gone with 17″ and up.  I personally like the 16″ because the tire selection is huge and you still get the big meat look with the tires and the nostalgia look with the wheels.  The trend of big wheels and low profile tires is becoming more popular with the Rodders every year.  The steel wheel with baby moons and trim rings starts to look goofy in 17″ and the early composites and one piece aluminum styles get lost after 17″.  So if you’re into the nostalgia look of the 50′s, 60′s and 70′s, plan on sticking with 14″, 15″ and 16″ wheels. 

4. Other things to think about

A.  Does your Rod have or do you plan to convert to disc brakes?  Some of the aftermarket brake systems are not very wheel friendly.  Make sure you check with the brake manufacturer to verify the compatibility between his brakes and your wheels.  I think some of these brake manufacturers think everyone buys brakes first, then builds a Rod to fit them.  I’d bet there were more Rods built around a set of wheels than brakes.  I’ve never had a brake manufacturer call me and ask for wheel profiles or samples to check against their brakes.  Seems like the logical thing to do.

B.  Check the bolt pattern (TECH Stuff #2) on your Rod to make sure the wheels you want are available in your bolt pattern.  There are a lot of Mopar guys out there that have stressed out trying to find a 5×4.00″ bolt pattern in the wheel style of their choice.

C.  Make sure you have verified the load rating of your wheel choice to the load requirements of your Rod (TECH Stuff #3). 

D. Last but certainly not least, check your clearance in the wheel well.  Check for fender clearance, brake clearance, suspension and steering component interference.  Refer to TECH Stuff #1 for more information on determining your wheel backspacing or offset.  Nothing is more irritating than tire rub when turning or going over bumps. 

In summary, do your homework before you decide on your wheels.  They can make your Rod.  And remember, don’t go to the prom with brown shoes.

  Here are some facts I picked up during my research; 

  1.  Air is composed of:

   A.  1% Water Vapor and other gases and escapes up to 250 times faster than Nitrogen.

B.  21% Oxygen and escapes 3-4 times faster than Nitrogen.

C. 78% Nitrogen and is the largest molecule in air, is dry and non-flammable.  Because of their large size, the nitrogen molecules are the least able to seep through the pores of the tire, therefore maintaining optimal inflation longer.By reducing the percentage of oxygen, water vapor and other gases in your tires from 21% to 7% or lower as compared to plain old air, your tires will hold proper inflation pressure 3-4 times longer.

2.  Increased Fuel Efficiency:

 Â By using Nitrogen in your tires, and maintaining proper inflation pressure, the rolling resistance is reduced, resulting in better fuel economy.  In fact, properly inflated tires can improve your gas mileage by about 3.3%.  I’ll take that any day.

1. Longer Tire Life:

By maintaining more consistent inflation pressure, and reducing rolling resistance, the tire doesn’t wear as fast from the heat caused by under-inflation. 

1. Increased Safety:

Under-inflated tires are the cause of 90% of blowouts.  Nitrogen provides more reliable inflation pressure and reduces blowout potential. 

5.  Improved TPMS (tire pressure monitoring system) Performance:

By 2008, the National Highway Traffic Safety Administration (NHTSA) has mandated that all new vehicles have a TPMS as standard equipment.  Most of the current systems being installed in new vehicles by the OEM’s, are put inside the tire.  They are an electronic device that puts out a signal that indicates if the tire pressure has dropped below the minimum required inflation pressure.  A warning light then flashes or lights up inside the vehicle, to inform the driver of a problem.  Using plain old air to inflate the tire can be a potential disaster for the TPMS monitor because of the water vapor from the plain old air.  As we all know, water and electronic components don’t play well together.  I do know that the cost to replace one of these TPMS devices is very pricey, not to mention the other three. 

1.  Helping the environment:

Don’t get me wrong, I’m not an environmental wacko, but I am for helping get rid of the smog and other things that are a result of toxic emissions released by our beloved rides.  Nitrogen used in tires can help.  It can decrease fuel consumption by reducing rolling resistance, it can increase tire life which will mean less tires need to be produced, which means less energy is used by tire manufacturers, less emissions from the trucks that deliver the tires and yada, yada, yada.  You get the picture.  In summary, I’m getting on the band wagon.  I’ve got 5 cars (one’s a work in progress) and a Motorhome.  I’m going Nitrogen and the 3.3% increase in gas mileage.  In the long run, I’ll buy less gas and fewer tires.  

 In today’s world, when you change the wheel and tire combination diameter, it affects a number of things with your ride. Not only will it change the speedo reading, but the ABS braking system, the engine management system and with some cars the suspension control system. Computers don’t take kindly to changes of input components.So to make sure you don’t alter the input from the wheel and tire combination, the diameter of the OEM combination needs to be maintained. To accomplish this you need to understand the meaning of Plus Sizing. A simple definition is to take the original wheel diameter and plus up from there. A Plus 1 conversion is upping the diameter of the original size by 1 inch (i.e. 14″to 15″). In some extremes I’ve heard of a Plus 9 conversion (i.e. 17″ to 26″). That’s a bit radical for me, but to each his own. Most tire and wheel dealers are very aware of the Plus Sizing concept and can guide you as to the proper tire size to fit your wheel diameter choice and maintain the original tire and wheel combination diameter. It’s pretty difficult to get the exact match, but if you are within 5% you’re okay.Now let’s discuss the Pro’s and Con’s of Plus Sizing.The Pro’s - First of all, you’ll be cool if you Plus Size. The bigger the diameter, the cooler you are (at least some folks think so). The biggest benefit from Plus Sizing is the increased road handling. By increasing the wheel diameter (and maintaining the original overall diameter), the height of the tire side wall deceases. This has the effect of less tire sway or roll, and increases the stability or cornering ability of your ride. Other than those 2 attributes, I’m hard pressed to come up with more Pro’s.The Con’s - The first thing that comes to mind is the loss of suspension. By deceasing the side wall of the tire, you will increase the effect of road bumps, pot holes, expansion joints and all the other deformities of our roads and highways. Road noise will be increased also. In addition to the loss of ride comfort, you will also experience a loss of free time. I come to this conclusion based on the theory that the bigger the wheel, the more time it requires to keep it shining. Another Con is the tire mounting folks that have to put these tires on these wheels (20′ and up) aren’t real thrilled with the whole concept. A few things to beware of when choosing to Plus Size. The larger the diameter of the wheel, the more difficult it is to meet the load requirements for a safe and reliable wheel. Some manufacturers solve the problem by adding material to the wheel so it will pass the performance standards (see TECH Stuff 3). By adding material, the weight of the wheel becomes heavier than the suspension the vehicle is designed to take and function properly. The tire and wheel are considered unsprung weight, and can cause excessive wear on the struts or shocks, bearings, spindles and brake systems.

Plus Sizing is not a bad thing when done properly.

Let’s cover the 3 types of finishes and how to maintain them.

 1.     Painted Finish – There are 2 types of paint used.  First and most popular is Powder Paint.  This is a paint that is applied in a powder form then baked at about 400 degrees.  The powder actually melts and becomes liquid for a short time then adheres to the wheel and creates a very hard surface with excellent coverage.  The second type is Liquid Paint.  It is sprayed in the conventional method and then baked in an oven.  Liquid paint normally results in a better finish with little or no orange peel effect.  Most high quality painted wheels are powder painted with the color and then liquid painted with a clear coat that gives the overall finish a lot of depth.  Maintaining Painted wheels can be accomplished with soap and water and a soft brush or cloth.  Make sure that the brake dust is rinsed away prior to using a brush or cloth because brake dust is very abrasive and can put small scratches in the finish.  Be very careful when sending your vehicle thru a car wash because they use coarse bushes to scrub the tires and they can get into the wheels and chew them up in a flash.

  2.     Chrome Plated – Chrome wheels are by far the easiest wheels to clean, if they are done frequently.  If they are not at least wiped clean with a damp cloth every 2-3 weeks, they accumulate road dust, brake dust and what ever else is out there, and then it requires chrome cleaner to remove the mess that hides the shine.  Chrome plating is a very tough and resistant finish, but it is not impervious.  Steel wheels that are chrome plated can still rust if they are subject to a lot of moisture or constant moisture.  Chrome plated aluminum wheels can oxidize from under the plating and cause pitting if not properly maintained.  The new technology used in chrome plating uses a 4 layer system.  First the wheel is plated with copper as a base and filler.  Then a semi-bright nickel is applied, followed by a bright nickel layer.  The final layer is the chrome.  The chrome is the thinnest of the layers but the hardest and the most resistant to the outside environment.Maintaining chrome wheels can be done with soap and water and a soft brush or cloth.  Again make sure to rinse away any brake dust prior to using a brush or cloth.  There are several chrome cleaners and polishes available to really put a shine on your wheels after washing them with soap and water.

   3.     Polished Aluminum – Owning and maintaining polished aluminum wheels is a real test to ones devotion and love of his ride.  After the wheel has been polished, that’s it.  There is no protective coating put on the wheel.  Aluminum oxidizes and dulls after a time.  The length of time depends on where you live, and how much moisture is in the air.  The dryer the climate the longer the finish will stay bright.  Maintaining polished wheels has only 2 requirements.  Elbow grease and a lot of time.  I will admit that a highly polished set of alloy wheels looks really bitchin.  I prefer chrome because I don’t want to work that hard and I’m too old to get down on my knees for that long, and it’s too hard to get back up.  Again there are several aluminum polishing products available and they pretty much all work.  That is with you supplying the muscle.

   There are a few other finishes that I didn’t cover that should be mentioned.  One being a machined finish aluminum wheel.  Maintenance is accomplished with soap and water and a soft brush or cloth.  Then there is a machined finished aluminum wheel that has a liquid clear coat finish applied after the machining.  Maintenance and care would be the same as a painted wheel. Remember, care and maintenance is your job not the manufacturer.  Don’t use harsh chemical cleaners and be careful of products that say “just spray on and rinse off”.  They most likely have some acid or etching chemicals that will destroy your wheels finish. 

Wheel Adapters:

There are 2 primary uses for adapters;

1.  The first and most common use is to change the bolt pattern.  Adapters are available that will change a 5-4.50” to a 5-4.75” or to a 5-5.00”, or the other way around.  There are several companies that make adapters that can offer about any combination within reason.  There are also adapters that will change a 4 hole pattern to a 5 hole.  Changing a 5 hole to a 6 hole is pretty much out of reason.  The drawback to using adapters is the thickness required to make them work properly.  The minimum thickness required is about 1.125” (depending on the length of your studs).  This will move your mounting surface out 1.125” and could cause some fender clearance problems.

 2.  The second use is if you need to move your wheels out from the existing mounting surface.  Adapters are available that have the same bolt pattern (i.e. 5-4.50” to 5-4.50”).  Adapters are the best way to accomplish moving your mounting face out.  Adapters can allow you to move the mounting face from 1.125” up to 2.500”.  Anything over 2.500” would require a little engineering, design and load calculation.

How they work;

Adapters are machined with a P.C.D. drilled with lug holes (60 deg. Conical Seat) (see TECH Stuff 4) to accept an open end lug nut.  There are studs inserted in another P.C.D. between the lug holes (see drawing).  The adapters are installed on the vehicle with lug nuts and tightened to the proper torque (TECH Stuff 4).  Make sure the vehicle studs or lug nuts do not extend past the mounting surface of the adapter.  The adapter becomes an extension of your original mounting surface.  Then mount your wheel and tighten it to the proper torque.

 Spacers:

 Spacers have gotten a bad rap over the years.  Some of the stuff is well deserved, but for the most part, spacers are not a bad thing and if used properly are a very useful tool to make your wheels fit properly.  A spacer over .313” (5/16) is not recommended.  That makes it tough when you need to move the wheel out from .313” to 1.125”.  That’s no man’s land (between a spacer and an adapter).  Oh well.  There are 2 basic rules to consider when using spacers;

1.  Always make sure you still have proper thread engagement of your lug nut and stud (TECH Stuff 4) after you have mounted the wheel on the vehicle with the spacer. 

2.  Choose a spacer that has a lot of mounting surface.  There are spacers being offered that are a “fit all” (4, 5 & 6 hole) type.  These look like a piece of swiss cheese and work about as well.  Also make sure the material is adequate (billet aluminum is best) (pot metal is worst).

Adapters and Spacers can be very handy tools that can help you get just the look you’re trying for with the wheels on your Rod.  When used properly, they are safe and reliable.

 

The following are the most common types of wheels offered by the aftermarket wheel industry.

1. Steel Wheels – This is where the aftermarket wheel industry got started. They consist of a steel outer/rim and a steel center. Chrome plating is very easy on this type because the rim and center are polished and chrome plated separately then pressed together and welded. Painting is also easy but is done after the wheel is assembled. Backspacing/offsets can be varied when the rim and center are pressed together. Trim rings and hub caps finish off these wheels nicely. Wire spoke wheels would fall in to this category but require much more maintenance in cleaning and runout (balancing).

2. Steel/Composite – This method of building wheels was started back in the 60’s. It consists of a steel rim and a cast aluminum center. This allows for more styling in the center. The aluminum centers are cast with steel cleats or inserts on the outer edges so it can be pressed into the steel rim and welded just like the Steel Wheels. These wheels are offered primarily chrome plated.

3. 1 Piece Cast Aluminum – This is now the most common wheel sold in the aftermarket. It offers the most variety of styling, sizes and finishes. These wheels can be painted, machined, polished or chrome plated. They are offered in sizes from 13” to 26” (28” & 30” are in development). These also offer a reasonable weight savings over Steel or Steel/Composite. The disadvantage of the 1 Piece Cast is the backspace/offsets are fixed in the mold.

4. Forged – This is the type that offers the lightest weight. Because of the forging process, the wheel can be built using much less material than a 1 Piece Cast. The styling is limited in comparison to a 1 Piece Cast and the tooling and manufacturing costs are much greater. These too can be painted, machined, polished or chrome plated. Because of costs the sizes offered are limited.

5. 2 Piece Aluminum – Also known as Billet, this type of wheel has been around for about 20 years. Like the Steel Wheel, it is made of a rim and center. The rims are rolled or spun and the centers are cast, forged or machined billet aluminum. The rim and center are pressed and welded together which also allows for a variation in backspace/offset. Forged and billet aluminum centers are typically stronger than cast centers because of the density of the aluminum. Finishing is limited to painting, machining or polishing. Chrome plating is difficult because the welding has problems created by the copper, nickel and chrome from the plating process.

6. 3 Piece Aluminum – These are also known as a Modular wheel. The rim is made up of 2 pieces, the front rim section and the rear section which are either spun or formed. The center can be of a cast, forged or machined billet type. The 3 pieces are assembled with the center sandwiched between the front and rear rim sections with bolts or rivets securing the pieces together. Styling is again limited, but finishing choices are like the 1 Piece Cast.

There are a few folks out there in the industry that will say wheels made by forging or from machined aluminum billet are stronger than cast wheels. That would be true if both wheels were made to the exact same design and dimensions. However, the strength or load carrying capacity and durability of a wheel comes from the design and manufacturing quality, based on the type of construction. The biggest advantage gained from forging or billet is weight. Because they are stronger, less material is needed. Regardless if it is steel, cast aluminum, forged or machined from billet, the wheel should still meet performance testing standards to be deemed safe and reliable.

1. Matching your lug nuts or bolts to your wheels.There are 3 basic type fastener seats;

1) Conical Seat – cone shape

2) Spherical Seat – round or ball shape

3) Flat Washer – commonly know as Mag Type

Be sure the fastener seat matches the seat in the wheel.

2. Proper Thread Size.

There are several different thread sizes used today by vehicle manufacturers;

12mm X 1.25

12mm X 1.5

12mm X 1.75

14mm X 1.5

14mm X 2.0

7/16” X 20

1/2” X 20

9/16” X 18

Two other things to remember; 1) do not put oil or lubricant on the threads of either the stud or lugs nuts/bolts, and 2) re-torque the lug nuts/bolts after 25-50 miles.

3. Proper Thread Engagement.

This is critically important. Make sure you have a minimum thread engagement of the diameter of the vehicle stud (as recommended by SAE). An example is if the stud size of your vehicle is ½” then you will need a minimum of ½” of threads into the lug nut. If for some reason you do not have this minimum then it is recommended that you use an ET Type nut (Extended Thread). ET Type nuts are useful when using spacers (that will be another subject in a future TECH Stuff).

4. Proper Torque (tightening).

This is also very important. Over tightening lug nuts/bolts can fatigue the vehicle studs or lug bolts. Use the SAE recommended torque listed below as a guideline;

1) 12mm = 70-80 ft. lbs.

2) 14mm = 85-90 ft. lbs.

3) 7/16 = 70-80 ft. lbs.

4) 1/2” = 75-85 ft. lbs.

5) 9/16” = 135-145 ft. lbs.