Which are the five lightest wheels for the 997 turbo?
Registered User
Joined: Dec 2009
Posts: 1,181
From: FL West Coast
Rep Power: 117
Which is stronger and lighter (same tensile strength): steel or titanium?
It's more about design and metallurgy. Forging allows for better design just because casting is less dense (more porous). You simply can't use casting to achieve the same thinness or strength you can with well designed forged metals.
Registered User
Joined: Mar 2008
Posts: 642
From: Kansas
Rep Power: 79
It's common sense and logic. Two wheels of the exact same size, specs and design. One cast the other forged. The forged wheel will be lighter. Its density would have to be less. Thats not even debatable dude.
I have been modding over 20 years. In that time I've seen lots of bent and broken wheels. More of them are forged. In fact, I've never bent or dented a cast wheel. Every forged wheel I've had suffered some type of issue...except the ones I have now. This is fact from experience....cast wheels are stronger than forged. Forged would be way stronger with equal density and weight of cast.
I have been modding over 20 years. In that time I've seen lots of bent and broken wheels. More of them are forged. In fact, I've never bent or dented a cast wheel. Every forged wheel I've had suffered some type of issue...except the ones I have now. This is fact from experience....cast wheels are stronger than forged. Forged would be way stronger with equal density and weight of cast.
Two identical wheels, one cast (A356), one forged (6061/T6), would weigh almost exactly the same. The forged wheel would just be 35-40% stronger due to the mechanical properties of the alloy. 6061 is a common alloy used in wheel making, but there are other MUCH stronger aluminum alloys that would be 100% stronger than the cast alloy.
So, when you properly engineer a forged wheel, you simply use less of the forged material to achieve the EXACT STRENGTH you need for a particular application. But you need to know exactly what you are doing.
This has NOTHING to do with alloy density. It has EVERYTHING to do with engineering.
The problem is that many aftermarket wheels, cast and forged, are not properly engineered. When they are not, they fail. OE cast (and forged) wheels are almost always properly engineered and subjected to rigorous testing. OEs are usually conservative and over-engineer the part somewhat. They rarely fail in service.
To eliminate poor engineering, some countries have instituted testing standards (TUV, SAE, DOT, JWL) to eliminate bad engineering before it winds up on your car. These standards vary from voluntary like SAE, to absolutely mandatory like the German TUV. (If you are caught in Germany with non-TUV wheels on your car, your car will be seized and impounded.)
In our country, the standards are weak and enforcement is almost non-existent. The US DOT is a self-policing standard. Therefore, many wheels make it to market that are poorly engineered. They often break.
Wheel engineering companies like BBS, OZ, Champion and ourselves rarely experience an in-service failure. These companies understand the metallurgy and the engineering, and regularly certify wheels with the German TUV. They employ skilled wheel engineers who produce wheels that are subjected to the most rigorous destructive testing imaginable. They know what they are doing.
In the end, FORGED means nothing. You can make terrible forged wheels from world-class forgings. This is all about the skill, experience and commitment of the manufacturer.
Last edited by Tech1_Mike; Mar 22, 2011 at 09:35 AM.
Former Vendor
Joined: Jan 2008
Posts: 226
From: San Diego
Rep Power: 0
This is a letter from our president, Alan Peltier from HRE Wheels regarding this weekend's race.
Following a highly successful pre-season testing program, the West Racing Lamborghini team experienced a mechanical issue in its first race of the season - during the early stages of the American Le Mans Series 12 Hours of Sebring endurance race. It appears that a mechanical failure with a wheel caused the team to pull out of the race early. Everyone at HRE and the West Racing Team is disappointed that the car did not finish its first big race of the season, but at this time we have not determined the cause of the problem and are waiting for the wheel to arrive at HRE headquarters for full analysis.
The competition-spec forged wheels on the West Racing Lamborghini are, like all HRE designs, engineered for maximum strength and durability. As we know, racing involves extreme conditions, and endurance racing is among the most punishing for the driver, the car and its components. HRE isn't racing because we know it’s easy. We're racing because we know it’s tough. If we expect to win, we have to push the envelope, and in the process, learn from our successes and failures. Rest assured, any lessons learned on the track will be applied to all our products for the street, resulting in the best wheels possible. As for this incident, once we have answers, we'll be transparent with the cause and the solution. Thank you for your patience and from avoiding speculation while we study the data. We will let you know when we know more.
Sincerely,
Alan Peltier
President
The competition-spec forged wheels on the West Racing Lamborghini are, like all HRE designs, engineered for maximum strength and durability. As we know, racing involves extreme conditions, and endurance racing is among the most punishing for the driver, the car and its components. HRE isn't racing because we know it’s easy. We're racing because we know it’s tough. If we expect to win, we have to push the envelope, and in the process, learn from our successes and failures. Rest assured, any lessons learned on the track will be applied to all our products for the street, resulting in the best wheels possible. As for this incident, once we have answers, we'll be transparent with the cause and the solution. Thank you for your patience and from avoiding speculation while we study the data. We will let you know when we know more.
Sincerely,
Alan Peltier
President
Registered User
Joined: Sep 2007
Posts: 1,625
From: fort lauderdale
Rep Power: 106
You are incorrect.
Two identical wheels, one cast (A356), one forged (6061/T6), would weigh almost exactly the same. The forged wheel would just be 35-40% stronger due to the mechanical properties of the alloy. 6061 is a common alloy used in wheel making, but there are other MUCH stronger aluminum alloys that would be 100% stronger than the cast alloy.
So, when you properly engineer a forged wheel, you simply use less of the forged material to achieve the EXACT STRENGTH you need for a particular application. But you need to know exactly what you are doing.
This has NOTHING to do with alloy density. It has EVERYTHING to do with engineering.
The problem is that many aftermarket wheels, cast and forged, are not properly engineered. When they are not, they fail. OE cast (and forged) wheels are almost always properly engineered and subjected to rigorous testing. OEs are usually conservative and over-engineer the part somewhat. They rarely fail in service.
To eliminate poor engineering, some countries have instituted testing standards (TUV, SAE, DOT, JWL) to eliminate bad engineering before it winds up on your car. These standards vary from voluntary like SAE, to absolutely mandatory like the German TUV. (If you are caught in Germany with non-TUV wheels on your car, your car will be seized and impounded.)
In our country, the standards are weak and enforcement is almost non-existent. The US DOT is a self-policing standard. Therefore, many wheels make it to market that are poorly engineered. They often break.
Wheel engineering companies like BBS, OZ, Champion and ourselves rarely experience an in-service failure. These companies understand the metallurgy and the engineering, and regularly certify wheels with the German TUV. They employ skilled wheel engineers who produce wheels that are subjected to the most rigorous destructive testing imaginable. They know what they are doing.
In the end, FORGED means nothing. You can make terrible forged wheels from world-class forgings. This is all about the skill, experience and commitment of the manufacturer.
Two identical wheels, one cast (A356), one forged (6061/T6), would weigh almost exactly the same. The forged wheel would just be 35-40% stronger due to the mechanical properties of the alloy. 6061 is a common alloy used in wheel making, but there are other MUCH stronger aluminum alloys that would be 100% stronger than the cast alloy.
So, when you properly engineer a forged wheel, you simply use less of the forged material to achieve the EXACT STRENGTH you need for a particular application. But you need to know exactly what you are doing.
This has NOTHING to do with alloy density. It has EVERYTHING to do with engineering.
The problem is that many aftermarket wheels, cast and forged, are not properly engineered. When they are not, they fail. OE cast (and forged) wheels are almost always properly engineered and subjected to rigorous testing. OEs are usually conservative and over-engineer the part somewhat. They rarely fail in service.
To eliminate poor engineering, some countries have instituted testing standards (TUV, SAE, DOT, JWL) to eliminate bad engineering before it winds up on your car. These standards vary from voluntary like SAE, to absolutely mandatory like the German TUV. (If you are caught in Germany with non-TUV wheels on your car, your car will be seized and impounded.)
In our country, the standards are weak and enforcement is almost non-existent. The US DOT is a self-policing standard. Therefore, many wheels make it to market that are poorly engineered. They often break.
Wheel engineering companies like BBS, OZ, Champion and ourselves rarely experience an in-service failure. These companies understand the metallurgy and the engineering, and regularly certify wheels with the German TUV. They employ skilled wheel engineers who produce wheels that are subjected to the most rigorous destructive testing imaginable. They know what they are doing.
In the end, FORGED means nothing. You can make terrible forged wheels from world-class forgings. This is all about the skill, experience and commitment of the manufacturer.
Registered User
Joined: Sep 2007
Posts: 1,625
From: fort lauderdale
Rep Power: 106
I repeat this, I've seen many bent and broken wheels. Most are forged. Rarely do u see a bent or broken cast wheel. Why?
Registered User
Joined: Mar 2008
Posts: 642
From: Kansas
Rep Power: 79
To reiterate:
Forged wheels are not PRONE to damage. Poorly engineered wheels are prone to damage. In your case, you bought some wheels that were not properly designed for the application and usage you intended.
What often happens is this:
People look for forged wheels because they are light. (If weight didn't matter, everyone would buy cheaper cast wheels.)
In an effort to squeeze the last possible ounce out of their design, some manufacturers go too far. They don't fully consider the usage, overestimate the strength of the alloy or don't fully understand the weight or loads of the vehicle. The result is the forged alloy gets overstressed. Any metal, (forged, cast, aluminum, titanium or steel) that gets overstressed will fatigue and fail.
Properly engineered wheels are NEVER overstressed and will last the life of the vehicle.
Hope that answers your question.
Registered User
Joined: Mar 2008
Posts: 642
From: Kansas
Rep Power: 79
You are correct. Any identical part made from a forged alloy will be SIGNIFICANTLY stronger than a cast part.(30-100%) But they will weigh about the same.
Registered User
Joined: Feb 2011
Posts: 176
From: london
Rep Power: 24
Mine and skandalis' dymags were under 6kgs for the front ones. I have the newer magnelium version and i will try to weight them again and post pictures.
Registered User
Joined: Dec 2009
Posts: 1,181
From: FL West Coast
Rep Power: 117
It may be (just speculating) that people using cast wheels don't put them to the rigors as they would a forged wheel. I know I wouldn't go curb hopping with cast wheels.
Registered User
Joined: Mar 2008
Posts: 642
From: Kansas
Rep Power: 79
Call me a Doubting Thomas, but I have to see those Dymags on a scale to believe the "under 6 kg" numbers.
Registered User
Joined: Sep 2009
Posts: 24
From: Heaven
Rep Power: 0
Care sharing about the load ratings HRE uses on their monoblock wheels for the Porsche Turbo?
Registered User
Joined: Sep 2007
Posts: 1,625
From: fort lauderdale
Rep Power: 106
I appreciate your personal anecdotes regarding forged wheels. However, this is not at all scientific and subject to real misinterpretation.
To reiterate:
Forged wheels are not PRONE to damage. Poorly engineered wheels are prone to damage. In your case, you bought some wheels that were not properly designed for the application and usage you intended.
What often happens is this:
People look for forged wheels because they are light. (If weight didn't matter, everyone would buy cheaper cast wheels.)
In an effort to squeeze the last possible ounce out of their design, some manufacturers go too far. They don't fully consider the usage, overestimate the strength of the alloy or don't fully understand the weight or loads of the vehicle. The result is the forged alloy gets overstressed. Any metal, (forged, cast, aluminum, titanium or steel) that gets overstressed will fatigue and fail.
Properly engineered wheels are NEVER overstressed and will last the life of the vehicle.
Hope that answers your question.
To reiterate:
Forged wheels are not PRONE to damage. Poorly engineered wheels are prone to damage. In your case, you bought some wheels that were not properly designed for the application and usage you intended.
What often happens is this:
People look for forged wheels because they are light. (If weight didn't matter, everyone would buy cheaper cast wheels.)
In an effort to squeeze the last possible ounce out of their design, some manufacturers go too far. They don't fully consider the usage, overestimate the strength of the alloy or don't fully understand the weight or loads of the vehicle. The result is the forged alloy gets overstressed. Any metal, (forged, cast, aluminum, titanium or steel) that gets overstressed will fatigue and fail.
Properly engineered wheels are NEVER overstressed and will last the life of the vehicle.
Hope that answers your question.
I am going to agree it has a lot to do with how its made. But my current wheels are heavier than most forged 20 in wheels....and worth it im my book. Screw that light weight stuff.
Registered User
Joined: Sep 2009
Posts: 24
From: Heaven
Rep Power: 0
I thought Carlsson Wheels were top quality but they bend and break easier than most any wheel out there. I had a set of Work wheels. They had a cast center and forged lip and barrel. The slightest touch bent the heck out of the lips. Same with Maya and Lowenhart. My current forged wheels are super strong because they have double rolled lips and barrels. Adds more weight but they are strong as heck. I have banged them several times and they still look good. No bends.
I am going to agree it has a lot to do with how its made. But my current wheels are heavier than most forged 20 in wheels....and worth it im my book. Screw that light weight stuff.
I am going to agree it has a lot to do with how its made. But my current wheels are heavier than most forged 20 in wheels....and worth it im my book. Screw that light weight stuff.
Aluminum is aluminum. It cannot be compressed and its density cannot be changed (relatively). A356 and 6061-T6 have very close densities but very FAR tensile and yield strengths. Forged 6061-T6 has almost twice the strength of A356. A square inch of 6061-T6 can hold twice as much "mass" than A356. Other factors are involved, of course.
Why cast wheels tend to be "stronger", in your misconception, than forged wheels is because:
1. Cast wheels are typically OEM wheels that are engineered with a very large headroom for disaster.
2. Cast wheel are typically smaller sizes than forged wheels since people tend to be afraid to run larger diameter of non-forged wheels for fear of bending them (ironic huh?)
3. Cast wheel, being smaller in general, tend to use larger tire profiles than forged wheels, having more impact absorption.
4. When you bend/crack a cast $300 wheel you won't make the same spectacle you would if you bend your $1500 high end wheel so less publicity is done.
Now, go get a set of 20" cast wheels and run 20 or 25 series tires and report back to us.
Keep in mind though that the same wheel (same design), engineered the same and rated at the same load will have the same strength whether it is cast or forged.
At the end of the day engineering plays a very large role in wheel strength. Maybe you have had a share of bad luck with them. You mentioned a lot of wheel brands that are not known for their ultra-high quality either and most of them are 2PC/3PC that the term "forged" is used very loosely when describing them.