Motorcycle Rim Cracks Could Mean Factory Defect

. Wednesday, January 12, 2011

By Billy Edwards
   Two Harley Davidson Ultra Classic motorcycles with different owners.  Same tires, same rims.  Similar rear rim cracks resulting in catastrophic rear  tire failures in both bikes traveling in different states one year apart.
   Coincidence?  Or a factory defect that may endanger others?
   A Harley rider from Michigan contacted the site recently to report the above. His bike, a 2001 Ultra Classic, experienced sudden rear tire failure in October 2009, in Michigan. A fellow Ohio rider on a 2002 Ultra Classic had a similar rear tire failure in September of 2010, traveling in Ohio.  Both rear rims showed similar, long cracks, pictured here: 
Ohio rider's rim
Michigan rider's rim
  Thankfully, both these guys – skilled, long-time riders – were able to bring their bikes under control after their tires suddenly deflated.  Not surprisingly, being that one is an engineer and the other an auto mechanic, they’re trying to find out what caused the rims of both bikes to crack.  Their dealers just scratched their heads. Harley Davidson had no comment. 
   Unlike tires, rims aren’t marked with the date of manufacture. If the rims weren’t made at the same time, were they made with the same batch of metal? Or with the same equipment?  Or under the same specifications?
   We’ve had two more reports to the website about rim issues, including a problem with rim bearings.
   We’ll share more information on this issue. Meantime, stay in touch if you hear anything.

Motorcycle GVWR Double-Speak

. Tuesday, November 16, 2010

By Billy Edwards

Motorcycle manufacturers speak out of both sides of their corporate mouths when it comes to the use of Gross Vehicle Weight Ratings for safe riding purposes.

I’ve posted before about the unfairness of holding consumers responsible for staying with GVWR limits due to confusion about how to locate (for some models), calculate or use this information correctly. I’ve put a handy Safe Weight Calculator on my website to make this a lot easier for riders. And it’s still the only guideline we get from manufacturers about weight issues, which affect maintenance and handling.  
But how useful is this information in determining at what point an overload will cause the motorcycle to fail and crash in some way?  Not very.  

On one hand, owner’s manuals clearly state - usually in more than one place – that for safety reasons, riders should not exceed the listed GVWR. A rider who crashes as the result of a tire defect and files a lawsuit can expect the manufacturer to show that overloading the bike was a factor – and try to pin the blame on the rider.

On the other hand, when I’ve had the chance to question manufacturers directly about the relationship between GVWR and safety, the following has come to light:

First - GVWR Isn’t All About Engineering 

GVWR’s are determined solely by the manufacturer at the beginning of the manufacturing process – the design phase – rather than at the end of the process. In other words, the bike isn’t built and then tested to a certain limit, beyond which the bike cannot be operated safely, and that becomes the GVWR. In reality, a designer will decide the GVWR up front and all the components will be built to that GVWR standard.
Okay, this seems to make sense, except for the fact that – at least as applied to American vehicle manufacturing in general – manufactures have been known to manipulate GVWR for other than sound engineering purposes. 

SUV’s are a perfect example. In the U.S., by law, vehicles weighing 6,000 pounds or less have to meet stricter roof crush standards. The law was meant to protect the majority of passengers. Many SUV’s however, were designed with GVWR’s slightly higher, allowing them to avoid this standard. Interestingly, SUVs also get a pass on meeting stricter gasoline efficiency standards because they are classified, for this purpose, as a “truck” (and under this same classification, they rate a tax exemption). Highway regulations that differentiate between cars and trucks (speed limits, weigh stations, lane passing), treat SUV’s as cars, however.  If you see politics, lobbyists and campaign contributions in this mix, it’s not your imagination. 

Second -  GVWR Isn’t an Absolute Safety Standard

While the above doesn’t apply to motorcycles, it’s not a stretch to believe the same political realities apply. Finally, you remember I started this post with noting that owner’s manufacturers make a big deal of warning riders to stay within the established GVWR for safety reasons. Following is an excerpt from a deposition I took with a Harley-Davidson engineer about GVWR that shows how inadequate this figure really is.   
Excerpts from Harley Davidson engineer deposition:

Q        To you as an engineer, what is the significance -- what is the meaning of GVWR?
A        That is one of the fundamental design inputs that we use in developing the motorcycle.  It's a performance target.  When our suspension group is developing the suspension, it's a target that they can go by in selecting appropriate spring and damping rates. When the brake group is designing the brakes, it's one of the fundamental vehicle parameters that they use as an input to assure that the brakes that they're designing are adequate for the bike, things like that.

Q        What should the GVWR mean to the final user of the motorcycle?
* * *
A        It could be used as an indication of how we have designed the bike and they -- a customer could use that as an input into how he is going to use the bike
* * *
Q        Is it a hard limitation on the expected use of the bike?
A        No.

Q        And why is it not a hard limitation on the expected use of the bike?
A        Well, for the two examples that I used a minute ago, the suspension -- as you incrementally load the bike, you're going to be making the suspension work incrementally harder.  There isn't anyplace in the loading curve where there's a threshold that the next pound is like throwing a switch and makes a significance difference.  But the more you load the suspension, the more you're going to bottom the suspension on big bumps.  And that's going to make the ride less comfortable.

           In terms of braking performance, again, there's nothing magic that occurs when you step over the line.  When we do our regulatory testing of brake systems, some of those regulations in some countries require that we do the testing with the vehicle loaded to gross vehicle weight rating.

           So we're testing the performance of the brake system under those conditions and we're measuring stopping distances from various speeds. As you load the bike more, those stopping distances will increase some.  Stopping distances will increase as you increase load.  As you decrease load, stopping distances will decrease.  So if I'm so low on the bike, no passenger, no luggage, I'm going to be under gross vehicle weight rating, I will probably be able to stop in less distance than we did when we did our regulatory testing.

           If you load the bike to 100 pounds beyond gross vehicle weight rating, it's going to take a little farther.  But to -- to stop.  But there isn't a magic number that says beyond this point, I change from safe to unsafe.

           Depending on the conditions and what's happening that's causing me to try to do a hard stop, I don't know how much distance I'm going to have in a particular condition, what speed I'm going to be going, and will I be able to stop in time to avoid the collision.

           If the bike is loaded less, I will have better odds of being able to stop in time.  If it's loaded more, I will be decreasing the odds that I will be able to stop in time.  But there's no -- again, there's no magic number at which it changes from safe to unsafe because I don't know what the requirements of a particular condition are going to be.

Q        Do I correctly interpret your answer to mean that loading an Ultra Classic like the motorcycle in question, 100 pounds beyond GVWR does not, in and of itself, change the motorcycle from a safe motorcycle to a dangerous motorcycle?

A        I would like to object to the term "dangerous motorcycle," but in general, that's correct.

Third - But GVWR Is All We’ve Got

In the end, staying within GVWR is a goal most related to long-term care and maintenance of your bike, and a reminder that weight affects bike performance and handling.  Also, staying within GVWR means you’re staying within the parameters of your tire load rating. And in the end, there is this: you may be able to ride for thousands of miles loaded beyond GVWR, but if you encounter a defective tire that fails, a fickle finger may point to you for overloading the motorcycle. 

Use a TPMS   

Finally, one last pitch for Tire Pressure Monitoring System: if you’re bike is equipped with tire pressure and temperature monitoring equipment (either from the factory or after-market), you are much more likely to catch that a tire is starting to deflate (either from a defect or from a small puncture) and avoid the catastrophic tire failure.

Here’s to your continued safe riding!


Motorcycle Tires: Age Matters

. Tuesday, September 14, 2010

You've Gotta Know the Date the Tire was Born

By Billy Edwards

Tire aging on cars has received attention recently, but I haven’t seen much of this information directed to motorcycle riders. One reason may be that m-motorcycle tires wear out much quicker than car tires – while a drive may rack up as much as 50,000 miles or more on car tires, we motorcyclists typically get 7,000 - 10,000 miles on our motorcycle tire. So for some, the motorcycle tire may not last long enough – from a chronological age standpoint – to worry about.

But … many of us may not put that much mileage on our motorcycle tires if the motorcycle is not our primary vehicle (you know, it’s just hard to take the kids to Grandma’s on a motorcycle), so it may take several years. Additionally, we generally don’t know the age of the tire when it’s put on our bike. This isn’t to say your dealer sold you a used tire instead of a new one. It’s just that from a tire aging standpoint, the tire begins to age as soon as it is born, which is when it comes out of the vulcanization press at the tire plant.

Basically, exposure to oxygen, ultra violet light (sun light), heat, and use all work to break down, wear out and harden the rubber compound used in the tires, whether the tire is on a bike or not.

How Old is Too Old?

So how old is too old? Well, it seems that there’s some debate about it. Some say ten years, some say six years. Some car tire companies and most safety advocates go with six years. Unfortunately, tire aging information from the tire companies is hard to come by. I’ve looked on both the Dunlop and Metzler motorcycle tire websites and I don’t find any information about tire aging.

For me, I’m going to stick with the 6-year guideline as a hard line, and if I’m somebody who likes to ride on the highways at highway speeds (and I am), I’m going to start getting uncomfortable at about three or four years.

Now that you’ve decided on your age limit, how do you determine how old your tire is? And the answer ain’t the date you bought it. You’ve gotta know the date your tire was born.

Tire Birthdates

Here the U.S. Department of Transportation comes to the rescue with its Tire Identification Code, stamped into every tire as it’s manufactured. The code is a combination of numbers that identifies the manufacturing location, tire size, manufacturer's code, and week and year the tire was manufactured. You can find the code on the sidewall of the tire, like the one pictured below.
If the tire was manufactured since 2000 or later, the last four numbers represent the week and the year the tire was made. In the case of the tire pictured, the numbers are 3505.The first two numbers are the week the tire was manufactured (the 35th week) or the last week of August. The last two digits are 05, which is 2005.

(To figure which week, divide by 4.3. Nailing it to the exact week isn’t necessary – if you get the correct month, or even within a month of the correct month, a tire is probably going to be OK as far as age goes. In other words, running it 6 years or running it 6 years and 1 month isn’t that much difference.)

Amaze Your Friends
Hopefully, nobody’s riding around on tires more than six years old, so information about tires older than 2000 isn’t necessary. But, just to be complete: tires manufactured during the 1980s had a three-digit code for the date, with the first two digits indicating the week, and the last digit indicating the year (355 would mean the 35th week of 1985) and tires manufactured in the 1990s had a three-digit date code but with a little triangle (Δ) after the code. So don’t ride on a tire from the 1980s or 1990s, but now you can amaze your friends by telling them exactly how old the tire is in the old tire swing in the back yard.

Safety Expert Hands “F” to Harley-Davidson Safe Weight Warning

. Friday, September 3, 2010

By Billy Edwards

A national safety analyst and Rice University Professor Emeritus gives an “F” to Harley-Davidson’s maximum weight warnings on its motorcycles. Kenneth Laughery, PhD., weighed in on the motorcycle safe weight issue as part of my lawsuit in the death of Stephen Gageby, of Butte MT.

Dr. Laughery is a Human Factors Professional, specializing in the design and effectiveness of warnings, labels and instructions. He confirmed what many in the motorcycle world already know: the way manufacturers deal with maximum weights and loads is grossly inadequate.

A motorcycle’s Gross Vehicle Weight Rating is usually posted on the bike’s frame. But this number is meaningless unless other statistics are known. Currently, owners of Harley Davidson touring bikes have to hunt through owner's manuals to find the bike's weight-related statistics, understand how the weights relate to each other, and calculate the difference to find their bike's maximum safe load. Honda owner's manuals directly state the model's maximum weight limit. But all this information is still buried in small print and not adequately available to buyers and riders.

Manufacturers state unequivocally in owner’s manuals that riders must not exceed safe weight limits. But in order to get this point across effectively, “it is critical that the maximum load be specified and an effective warning system address the safety issues associated with exceeding the weight capacity,” Dr. Laughery writes.

Specifically, he notes, “The owner’s manual for the Harley-Davidson Ultra Classic motorcycle was the only source of information regarding the value of the GVWR and the weight of the motorcycle. While this information enables the user to calculate the maximum load value…it requires the user to perform an additional task of determining the relevant values and carrying out the calculation to determine if the GVWR is being violated. There is substantial research reported in the peer-reviewed scientific literature that documents the negative effects of such (requirements) on warning compliance.”

Then he confirms what most of us already know. “It is well documented in the research literature that a substantial majority of people do not read vehicle owner’s manuals cover to cover. Rather, such manuals are used as reference documents for obtaining information when it is needed. Thus, unless the user is provided a reason to seek particular safety information in the owner’s manual, such as maximum load capacity, it is unlikely the information in the manual will be addressed. “

The problem led to the creation of my website’s Safe Weight Calculator ( Most large touring models of bikes are represented, since these bikes are frequently loaded for long trips and may carry more than one rider. Just plug in passenger and cargo weights, and the calculator will tell you if you are within the model’s safe weight limits.

Don’t you think it’s time motorcycle manufacturers posted clear, meaningful weight information that riders can use to stay safe?

Dunlop 402 Among Array of Problem Motorcycle Tires

. Friday, August 20, 2010

By Billy Edwards

Dunlop brand motorcycle tires manufactured at the company’s Buffalo, NY plant, have experienced an “alarming array of incidents” involving dangerous bead conditions, according to tire expert William J. Woehrle, head of Tire Forensics Investigations and former tire plant executive and engineer.

D402 tire failure crash
Woehrle’ report, written in 2010, lists nine incidents of failures of Dunlop tires made at the Buffalo plant “where the only reasonable explanation for the failure was a severe drop in pressure caused by a defective bead.” The incidents occurred between 2002 and 2009. Many other incidents have been reported to my website, dealing mainly with Goodyear Dunlop D402 tires.

Bead defects are supposed to be identified during the manufacturing process and the bad tires tossed. Obviously, human and process failures being what they are, that doesn’t always happen...

Sturgis Crashes should be Investigated As Possible Tire Defect Problems

. Thursday, August 12, 2010

By Billy Edwards

Tragedy struck the Sturgis Motorcycle Rally yesterday. At least three people were killed in separate accidents, and the South Dakota Highway Patrol attributed the crashes to problems with the motorcycles’ rear tires. According to the patrolmen, witnesses reported the tries suddenly went flat, lost air pressure or blew.

These should be investigated as possibly related to a tire defect. It can happen easily, as my years of experience has taught me. My evidence in a case I recently settled over a defective Goodyear Dunlop 402 tire, showed how these tires, along with many others, can fail. Following is a summary of parts of a report I received from one of my investigators.

Dunlop brand motorcycle tires manufactured at the company’s Buffalo, NY plant, have experienced an “alarming array of incidents” involving dangerous bead conditions, according to tire expert William J. Woehrle, head of Tire Forensics Investigations and former tire plant executive and engineer.

Woehrle’ report, written in 2010, lists nine incidents of failures of Dunlop tires made at the Buffalo plant “where the only reasonable explanation for the failure was a severe drop in pressure caused by a defective bead.” The incidents occurred between 2002 and 2009. Many other incidents have been reported to my website, dealing mainly with Goodyear Dunlop D402 tires.

Bead defects are supposed to be identified during the manufacturing process and the bad tires tossed. Obviously, human and process failures being what they are, that doesn’t always happen. The Woehrle report was in response to one of my cases involving the death of Stephen Gageby of Butte, Montana. He determined the proximate cause of Stephen’s catastrophic tire deflation as a “run-soft failure” caused by leaks between the tire bead and the rim flange. Manufacturing defects that caused the leaks “are readily and immediately visible upon visual inspection at the tire factory,” according to the report.

I wanted to share with you his good explanation of the mechanics of a tire separation and run-soft failure:

“A tire is a laminate, similar to a piece of plywood. In a tire, these laminated layers consist of ‘plies’ of chord material, along with several layers of different types of rubber. If a tire is to structurally fail, a common failure mode is a delaminating of two or more of these layers, just as with a piece of plywood. When such a delaminating process occurs with a tire, it is called a ‘separation.’

This separation emerges from 5 influences: 3 stresses (load, inflation pressure, and speed), plus heat and oxygen When an inflated tire is loaded, a critical shear stress emerges in the belt rubber and ply rubber, with the highest level being between the belts. Higher speed increases the stress, due to the increased rate of flexing (cycles/second), as well as the increased centrifugal force. This is compounded by the higher temperatures resulting from these stresses, since rubber adhesion and strength decreases with increasing temperature. Last, but not least, rubber ages from an oxidation process. The source of the oxygen is the tire inflation pressure, which permeates past the carcass and belts at the rate of 1-2 PSI/month at normal inflation pressures. This slowly but steadily deteriorates the rubber, and reduces its strength and adhesion. Furthermore, the rate of oxidation increases with increasing temperature.

The aging of rubber via this oxidation process has been widely acknowledged and understood. The issue of tire aging has received even greater attention in recent years, as the result of the TREAD act and the emergence of FMVSS 139. The tire industry has told NHTSA that, while there are many aging mechanisms acting on a tire, there are only 2 that really matter. One of them is chemical aging, which involves changes in rubber due to mechanical stress/strain. Since the area in the shoulder region has the highest stress/strain, mechanical aging effects are the greatest in this area. This type of aging is dependent on the number of cycles of stress/strain (flexing).”

Keeping this in mind, most tires are safe. But defects leading to leaks and separations do occur. Do you have a question about tire safety? Do you want to know more about the Woehrle results?

Tire Pressure & Temperature Gauges Save Lives

. Tuesday, August 10, 2010

By Billy Edwards

Tire pressure and temperature gauges should be standard equipment on all motorcycles. This is especially important on large touring bikes that traditionally carry more weight over longer periods of time. If this were the case, Stephen Gageby, of Butte, Montana – big man and big Harley enthusiast – might still be alive.

The technology to provide operator feedback about tire pressures and temperature has been commercially available since about 1999. Gradually it’s become standard safety equipment on all U.S. cars and light trucks, and on some motorcycles, notably Honda and BMW. But not on Harley-Davidson bikes and others, which is ridiculous. Motorcyclists know how important tire safety is and experienced riders check tire pressures before they ride. But pressures vary with temperatures, which change based on many factors.

Unfortunately, the systems that provide tire pressure monitoring on motorcycles are limited (without a programming change) to displaying temperature limits. An exception is a system made by Schrader-Bridgeport, a leader in the industry, that allows operators to set up temperature alarms. This system, available since 2000, is readily available as a retrofit.

The rear tire on Stephen Gageby’s 2003 Harley Davidson Ultra Classic was a Goodyear-Dunlop D402. On a beautiful Spring day in 2007, while riding to a son’s birthday party, the tire failed – Stephen was killed and his wife, Karla, was seriously injured. In the lawsuit I filed for Karla against Goodyear Dunlop and Harley Davidson, we alleged that the tire had a defective bead, causing the tire to fail (That lawsuit settled in July, 2010).

According to Applied Technical Services, Inc., a large, well-respected forensic engineering company, “The event involving the rear tire failure of Mr. Gageby’s motorcycle, could have, to a reasonable degree of engineering certainty, been avoided had a means of monitoring and alarming either a lack of inflation pressure or a dangerous rise in tire temperature been available to Mr. Gageby.”

In other words, if Harley Davidson had incorporated a safety system standard on most tired vehicles in the U.S. today, my client might still be alive. If you own a Harley, ask your dealer about a retrofit.