Good NY Times overview on the tire/wheel situation these days
10-11-2004, 01:41 PM
#1
Senior Member
Thread Starter
Join Date: Mar 2000
Posts: 7,469
Likes: 0
Received 0 Likes
on
0 Posts
Good NY Times overview on the tire/wheel situation these days
It's a registration-only site, so I'm providing the text in the interest of fair use and research.
October 10, 2004
G.M. Hopes to Bring Home the Bling
By TIM MORAN, NY Times
TODAY'S urban street fashions go well beyond velour track suits, limited-edition Nikes and the big-bling theory. On the road, hip-hop style requires oversize wheels and ultra-low-profile tires.
While these accessories - "dubs" in street slang - are hotter than ever, they also have downsides: the installation of wheels and tires that are much wider or bigger in diameter than the original factory equipment can compromise the antilock brakes and affect the traction control and electronic stability systems. That can make a top-heavy vehicle more prone to roll over.
The handling changes even when larger-diameter wheels are coupled with lower-profile tires - those with short sidewalls relative to their width - and the overall diameter stays the same as the factory equipment. Engineers at General Motors say that putting big wheels on a vehicle designed for smaller ones can affect handling in extreme maneuvers - swerving to avoid a child, for instance.
"When it comes to that once-in-a-lifetime situation, it might not handle quite like you hoped," said Frank Taverna, G.M. engineering group manager for vehicle dynamics.
G.M. is certainly not against big wheels. To the contrary, the company is raising questions about aftermarket dubs to call attention to its own new line of 20-inch wheels. G.M. is offering 25 designs, and plans some 50 designs for 35 vehicles by the end of 2005. Retail prices for a set of its plus-size wheels and tires, including installation, range from $2,700 to $3,950.
G.M. is not alone: lured by the high profits of custom accessories, automakers including Nissan, Mercedes-Benz and the Scion division of Toyota are offering larger wheels to customers who want to personalize their cars. Even venerable Rolls-Royce is embracing the trend: its $320,000 Phantom can be ordered with 21-inch aluminum wheels that "add a dramatic edge to the look of the motorcar."
Automakers say there is a big difference between their wheels and what's generally available in the booming aftermarket. Even though auto manufacturers' wheels are often made by the same companies that produce dubs for independent brands, G.M. says its extensive testing and engineering matches the wheels better to specific vehicles, to ensure that the cars operate safely within federal guidelines.
But while drivers may think some agency is watching out for problems caused by tire and wheel changes, that is not the case. When it comes to modifying original equipment, "we usually refer people, and defer, to what is written in the owner's manual," said Liz Neblett, a spokeswoman for the National Highway Transportation Safety Administration. She said the agency had no continuing investigations of oversize wheels.
The largest G.M. wheels are 20 inches, which a spokesman, Tom Henderson, pointed out is 4 inches larger than the standard 16-inch wheels on most production trucks. "We don't go larger than 20 inches because, even if we can make it fit, we haven't been able to validate the safety aspects for the overall vehicle," he said.
The aftermarket crowd is in a different league, with wheels of 20 and 22 inches considered ordinary. The style-conscious have moved on to 24-, 25-, 26- and even 28-inch wheels. Wheels are measured in inches and are described by their diameter; most passenger car wheels range from 12 to 16 inches.
Independent wheel designers are skeptical of automakers' claims that the factory wheels are better and safer. They say their own designs, combined with high-quality low-profile tires that duplicate the load range of the original tires, are safe.
"All you're doing is compensating with a smaller-profile tire for a bigger wheel," said Fernando Guzman, marketing director of WTW Inc. in Santa Fe Springs, Calif. A privately held company with annual sales of more than $20 million, WTW designs and markets wheels, but does not manufacture them.
WTW's brands include Giovanna, Gianelle and GFG wheels, with prices from $600 to $2,300 apiece - tires not included.
Mr. Guzman says WTW invests heavily to develop its wheels, often supplementing auto manufacturers' data by buying first-run new cars or trucks to use as physical models for precision fitting. Some carmakers provide preproduction vehicles to aftermarket companies, as well.
The market is big and getting bigger. Custom wheels account for more than $3.2 billion in annual sales. Performance wheel and tire exhibits take up 22 percent of the display space at the huge annual trade show of the Specialty Equipment Market Association, known as SEMA. This year's show, scheduled for Nov. 1-4 in Las Vegas, will have wheel exhibits from 272 companies, said Christopher J. Kersting, president of SEMA.
"A lot of the popular wheel and tire customization combos are actually within the vehicle manufacturers' specs," Mr. Kersting said. Still, another SEMA executive present during test-track demonstrations this summer at the G.M. proving grounds in Milford, Mich., said buyers should do their homework.
"When you go from 18 to 20, I'm not too worried, but when you just go up to 24, that person needs to educate themselves," said Carl Scheffer, a vice president of SEMA.
Mr. Kersting said that consumers should be careful to buy from professional installers. That advice is backed up by engineers who point out that control of a car comes down to the small area where rubber meets the road.
"The reality of it is, the only place your vehicle interfaces with the road is through that contact patch," said David Cowger, manager of G.M.'s tire engineering group. Changing that patch changes the handling.
Indeed, in testing arranged by G.M. at its proving grounds, drives of identical pickups equipped three ways - with ordinary wheels, with G.M. specialty wheels and with a set of dubs bought over the Internet - showed clear differences in ride and handling.
It is not just a case of whether the wheels and tires fit within the fenders. Bigger wheels put more stress on a car's suspension, brakes and steering. G.M.'s installations include electronic modifications to these systems as well as to the speedometers and odometers, since their readings are also affected by a change in wheel size. A do-it-yourself installer is unlikely to be able to make these modifications.
Big wheels may also reduce the amount of weight the vehicle can carry, and can increase fuel use.
A car's efficiency suffers because bigger wheels change the physics of acceleration and deceleration, said an independent consultant, Jacques Bajer of Tire Systems Engineering in Grosse Pointe, Mich.
Mr. Bajer noted that Formula One cars, which change speed constantly, use tiny 13-inch wheels within big tires for faster acceleration. Bigger wheels take more energy to spin. The more tire there is, rather than wheel, the more efficient the combination is. And Mr. Bajer says that low-profile tires leave the expensive wheels vulnerable to damage from potholes.
G.M. engineers say wheel-tire combinations that are too large can also be so stiff and road-hugging that they "trip" the car and cause a rollover.
As well, larger wheels can change the way a car or truck absorbs the energy of a crash. If a dub-equipped vehicle hits a solid obstruction, the larger wheels and low-profile tires may transmit the crash energy faster than usual. G.M. engineers say they found in testing that putting bigger wheels on some pickups requires a beefier "jounce pad," a rubber cushion for the axle on big bumps.
Drivers also face the age-old paradox of sacrificing comfort for style. Larger wheels tend to make a car more responsive, but may also make it feel twitchy and ride harshly.
Mr. Guzman of WTW wishes the automakers well in their efforts to attract customizers, but says the independents have an edge with customers who are looking for extreme style and exclusivity. Twenty-inch wheels wearing the Chevy bow tie are unlikely to please this market.
"If it's hard to get, you want it more," he said. "If it's easy to get, who wants it?"
Still, the aftermarket is happy to welcome Detroit to its neighborhood. "They are asking people to change their original wheels," Mr. Kersting of SEMA said. "Our industry couldn't ask for better marketing."
Copyright 2004 The New York Times Company
October 10, 2004
G.M. Hopes to Bring Home the Bling
By TIM MORAN, NY Times
TODAY'S urban street fashions go well beyond velour track suits, limited-edition Nikes and the big-bling theory. On the road, hip-hop style requires oversize wheels and ultra-low-profile tires.
While these accessories - "dubs" in street slang - are hotter than ever, they also have downsides: the installation of wheels and tires that are much wider or bigger in diameter than the original factory equipment can compromise the antilock brakes and affect the traction control and electronic stability systems. That can make a top-heavy vehicle more prone to roll over.
The handling changes even when larger-diameter wheels are coupled with lower-profile tires - those with short sidewalls relative to their width - and the overall diameter stays the same as the factory equipment. Engineers at General Motors say that putting big wheels on a vehicle designed for smaller ones can affect handling in extreme maneuvers - swerving to avoid a child, for instance.
"When it comes to that once-in-a-lifetime situation, it might not handle quite like you hoped," said Frank Taverna, G.M. engineering group manager for vehicle dynamics.
G.M. is certainly not against big wheels. To the contrary, the company is raising questions about aftermarket dubs to call attention to its own new line of 20-inch wheels. G.M. is offering 25 designs, and plans some 50 designs for 35 vehicles by the end of 2005. Retail prices for a set of its plus-size wheels and tires, including installation, range from $2,700 to $3,950.
G.M. is not alone: lured by the high profits of custom accessories, automakers including Nissan, Mercedes-Benz and the Scion division of Toyota are offering larger wheels to customers who want to personalize their cars. Even venerable Rolls-Royce is embracing the trend: its $320,000 Phantom can be ordered with 21-inch aluminum wheels that "add a dramatic edge to the look of the motorcar."
Automakers say there is a big difference between their wheels and what's generally available in the booming aftermarket. Even though auto manufacturers' wheels are often made by the same companies that produce dubs for independent brands, G.M. says its extensive testing and engineering matches the wheels better to specific vehicles, to ensure that the cars operate safely within federal guidelines.
But while drivers may think some agency is watching out for problems caused by tire and wheel changes, that is not the case. When it comes to modifying original equipment, "we usually refer people, and defer, to what is written in the owner's manual," said Liz Neblett, a spokeswoman for the National Highway Transportation Safety Administration. She said the agency had no continuing investigations of oversize wheels.
The largest G.M. wheels are 20 inches, which a spokesman, Tom Henderson, pointed out is 4 inches larger than the standard 16-inch wheels on most production trucks. "We don't go larger than 20 inches because, even if we can make it fit, we haven't been able to validate the safety aspects for the overall vehicle," he said.
The aftermarket crowd is in a different league, with wheels of 20 and 22 inches considered ordinary. The style-conscious have moved on to 24-, 25-, 26- and even 28-inch wheels. Wheels are measured in inches and are described by their diameter; most passenger car wheels range from 12 to 16 inches.
Independent wheel designers are skeptical of automakers' claims that the factory wheels are better and safer. They say their own designs, combined with high-quality low-profile tires that duplicate the load range of the original tires, are safe.
"All you're doing is compensating with a smaller-profile tire for a bigger wheel," said Fernando Guzman, marketing director of WTW Inc. in Santa Fe Springs, Calif. A privately held company with annual sales of more than $20 million, WTW designs and markets wheels, but does not manufacture them.
WTW's brands include Giovanna, Gianelle and GFG wheels, with prices from $600 to $2,300 apiece - tires not included.
Mr. Guzman says WTW invests heavily to develop its wheels, often supplementing auto manufacturers' data by buying first-run new cars or trucks to use as physical models for precision fitting. Some carmakers provide preproduction vehicles to aftermarket companies, as well.
The market is big and getting bigger. Custom wheels account for more than $3.2 billion in annual sales. Performance wheel and tire exhibits take up 22 percent of the display space at the huge annual trade show of the Specialty Equipment Market Association, known as SEMA. This year's show, scheduled for Nov. 1-4 in Las Vegas, will have wheel exhibits from 272 companies, said Christopher J. Kersting, president of SEMA.
"A lot of the popular wheel and tire customization combos are actually within the vehicle manufacturers' specs," Mr. Kersting said. Still, another SEMA executive present during test-track demonstrations this summer at the G.M. proving grounds in Milford, Mich., said buyers should do their homework.
"When you go from 18 to 20, I'm not too worried, but when you just go up to 24, that person needs to educate themselves," said Carl Scheffer, a vice president of SEMA.
Mr. Kersting said that consumers should be careful to buy from professional installers. That advice is backed up by engineers who point out that control of a car comes down to the small area where rubber meets the road.
"The reality of it is, the only place your vehicle interfaces with the road is through that contact patch," said David Cowger, manager of G.M.'s tire engineering group. Changing that patch changes the handling.
Indeed, in testing arranged by G.M. at its proving grounds, drives of identical pickups equipped three ways - with ordinary wheels, with G.M. specialty wheels and with a set of dubs bought over the Internet - showed clear differences in ride and handling.
It is not just a case of whether the wheels and tires fit within the fenders. Bigger wheels put more stress on a car's suspension, brakes and steering. G.M.'s installations include electronic modifications to these systems as well as to the speedometers and odometers, since their readings are also affected by a change in wheel size. A do-it-yourself installer is unlikely to be able to make these modifications.
Big wheels may also reduce the amount of weight the vehicle can carry, and can increase fuel use.
A car's efficiency suffers because bigger wheels change the physics of acceleration and deceleration, said an independent consultant, Jacques Bajer of Tire Systems Engineering in Grosse Pointe, Mich.
Mr. Bajer noted that Formula One cars, which change speed constantly, use tiny 13-inch wheels within big tires for faster acceleration. Bigger wheels take more energy to spin. The more tire there is, rather than wheel, the more efficient the combination is. And Mr. Bajer says that low-profile tires leave the expensive wheels vulnerable to damage from potholes.
G.M. engineers say wheel-tire combinations that are too large can also be so stiff and road-hugging that they "trip" the car and cause a rollover.
As well, larger wheels can change the way a car or truck absorbs the energy of a crash. If a dub-equipped vehicle hits a solid obstruction, the larger wheels and low-profile tires may transmit the crash energy faster than usual. G.M. engineers say they found in testing that putting bigger wheels on some pickups requires a beefier "jounce pad," a rubber cushion for the axle on big bumps.
Drivers also face the age-old paradox of sacrificing comfort for style. Larger wheels tend to make a car more responsive, but may also make it feel twitchy and ride harshly.
Mr. Guzman of WTW wishes the automakers well in their efforts to attract customizers, but says the independents have an edge with customers who are looking for extreme style and exclusivity. Twenty-inch wheels wearing the Chevy bow tie are unlikely to please this market.
"If it's hard to get, you want it more," he said. "If it's easy to get, who wants it?"
Still, the aftermarket is happy to welcome Detroit to its neighborhood. "They are asking people to change their original wheels," Mr. Kersting of SEMA said. "Our industry couldn't ask for better marketing."
Copyright 2004 The New York Times Company
10-11-2004, 02:01 PM
#3
Senior Member
Join Date: Dec 2000
Posts: 5,218
Likes: 0
Received 0 Likes
on
0 Posts
boy, loads of inaccurate statements
First, bigger wheels don't necessary equal more weight. Their insinuation that F1 uses 13" wheels because they are lighter when in reality it's to limit the size of the brakes inside said wheels. I'm willing to wager a well-made, forged wheel will weight a hell of a lot less than a cheapy, cast GM wheel.
Secondly, that all wheels you buy off the internet are not properly matched to your vehicle. I think that it's A LOT easier to buy wheels with the wrong offset and the wrong load rating on the tires. That's especially true for your average consumer who doesn't have the first clue about wheels and tires.
The article sounds more like a GM-PR dept written ad than an independently researched article.
Secondly, that all wheels you buy off the internet are not properly matched to your vehicle. I think that it's A LOT easier to buy wheels with the wrong offset and the wrong load rating on the tires. That's especially true for your average consumer who doesn't have the first clue about wheels and tires.
The article sounds more like a GM-PR dept written ad than an independently researched article.
10-11-2004, 02:34 PM
#4
actually most of this piece is factual and supported by......
simple physics.
regardless of why formula one cars use smaller wheels, they do benefit from quicker acceleration and deceleration and quicker steering response as a result. with all other factors constant, the smaller the unsprung weight (wheel, tire, brake and so on) the quicker the car and better the suspension will perform.
while it is possible to manufacture a large diameter wheel that is ligher than oems...the larger wheel still might be negatively affected, since acceration and angular velocity are affected by a square or cube of radius and how far the weight is from the center.
i doubt that few if any wheel makers make these calculations....except for race track wheels.
from my read every issue or point made in the piece is factually correct.
there plenty of examples of suvs rollovers where big wheels and low profile tires play a critical part. low aspect ratio tires are less protective of wheels....and so on. the piece is right on target.
physics may not be bling bling but it does support the facts.
except for your noggin'
the entire motoring experience is physics and chemistry. most mods are purchased without understanding the negative potential and most "seat of the pants" judgements are based on, well.....what's in the seat of your pants.
virtually nothing in the piece is gm specific either.
cheers
regardless of why formula one cars use smaller wheels, they do benefit from quicker acceleration and deceleration and quicker steering response as a result. with all other factors constant, the smaller the unsprung weight (wheel, tire, brake and so on) the quicker the car and better the suspension will perform.
while it is possible to manufacture a large diameter wheel that is ligher than oems...the larger wheel still might be negatively affected, since acceration and angular velocity are affected by a square or cube of radius and how far the weight is from the center.
i doubt that few if any wheel makers make these calculations....except for race track wheels.
from my read every issue or point made in the piece is factually correct.
there plenty of examples of suvs rollovers where big wheels and low profile tires play a critical part. low aspect ratio tires are less protective of wheels....and so on. the piece is right on target.
physics may not be bling bling but it does support the facts.
except for your noggin'
the entire motoring experience is physics and chemistry. most mods are purchased without understanding the negative potential and most "seat of the pants" judgements are based on, well.....what's in the seat of your pants.
virtually nothing in the piece is gm specific either.
cheers
The following users liked this post:
Billy_Madison (12-26-2019)
10-11-2004, 02:52 PM
#5
Senior Member
Thread Starter
Join Date: Mar 2000
Posts: 7,469
Likes: 0
Received 0 Likes
on
0 Posts
Example of bigger is better mentality
was stuck in traffic the other day on the freeway next to a gigantic new Ford 4-door pickemup. Had huge aftermarket wheels and tires, yet the decals on the side of the bed screamed out "Off Road Package." Yeah, that's a handling combination made in heaven.
10-11-2004, 04:58 PM
#6
Elder Member
Join Date: Mar 2001
Posts: 11,968
Likes: 0
Received 0 Likes
on
0 Posts
Re: F1 wheels
If I recall correctly, a Bridgestone F1 tire engineer said the optimum wheels in F1 would be 18" front and 20" rear. Handling and response would be improved so much, though, the driver wouldn't be able to endure the g loads for an entire race.
And I agree that the article sounds more like something from the GM-PR dept.
And I agree that the article sounds more like something from the GM-PR dept.
10-12-2004, 05:39 AM
#7
AudiWorld Expert
I agree with you on this. And GM is right about adding bigger wheels to the vehicles.
The wheel companies do not have to do any where near the testing a car company has to do to market a wheel.
Trending Topics
10-12-2004, 07:06 AM
#8
New Member
Join Date: Apr 2001
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
look up "moment of inertia" in a college physics book...
For wheels of the same mass, the smaller overall diamerter will require less torque to change its angular momentum. Although I am an aftermarket wheel buyer, bigger wheels do have this side effect. I beleive Tirerack did some independent testing of huge wheels on an SUV and had an incredible increase in stopping distance.
-Rob
-Rob
