run flats and ride
03-04-05, 09:07 PM
#18
Guest
Posts: n/a
Whoa fellas. Slow down
. Run Flats are seen as the future. As cars need the trunk space and weight savings of no spare. THey are not perfect but EVERY car maker is going towards this way. With a GS hybrid coming, those batteries have to stow somewhere as well. The new Chevy Z06 uses them., the BMW Z4, the BMW 5 to name a few.
http://autos.msn.com/advice/article....21164&src=News
Run-Flat Tires:
A New Standard Rising Click Here!
2003 Chevrolet Corvette Coupe The Chevrolet Corvette celebrates its 50th anniversary in 2003 but also its 10th model year as run-flat tire pioneer.
by Editors of MSN Autos Canada / U.S.
In a few years, accidents due to tire blowouts should become a thing of the past, along with spare wheels and cumbersome jacks.
2004 Toyota Sienna
The new 2004 Toyota Sienna AWD minivan is the first mainstream, family-oriented vehicle to benefit from the undeniable safety of standard run-flat-type tires.
PAX
This cutaway photo of a tire using the Michelin-developed PAX system clearly shows the solid "ring" that supports the tire tread in the event of a pressure loss.
advertisement
Gentex pressure monitor
Air pressure monitors are mandatory with run-flat tires. One such product is a new Gentex mirror-mounted display.
BMW Z8
With wide tires, big wheels and a small trunk, BMW's exotic Z8 sports car is a natural for run-flat performance tires as standard fitment from day one.
Michelin PAX system
The key elements of Michelin's PAX system are special wheels with tire bead locks and a solid "insert" that can support its share of vehicle weight.
Magic Ring
If this same tire loses inflation pressure, its sidewalls flex and the PAX syst***s polyurethane/rubber "magic ring" enables the vehicle to keep rolling.
Goodyear F1 Steel
Goodyear's F1 Steel tire was the first run-flat tire offered as standard fitment on a production model, the fifth generation Corvette, in 1997.
Mini Cooper S
The 2003 MINI Cooper S comes standard with 16-inch, all-season run-flat tires or these optional 17-inch performance run-flats on Minilite-replica alloy wheels.
When J.D. Power and Associates asked thousands what they most wanted in a new vehicle for a 2001 study, 87 per cent of respondents said: run-flat tires, making these the most desirable feature by far.
These so-called run-flat, extended mobility, continuous mobility or zero-pressure tires can be driven at normal speeds, for some distance, without any air pressure in the event of a puncture, a deep cut or the ravages of just about any other road hazard.
By contrast, "self-sealing" tires use different methods to preserve inflation, but there is a definite limit to the severity of the damage they can incur. These tires simply cannot be driven without any inflation pressure.
In the Name of Safety
The original idea of an "anti-puncture" tire appeared in a patent request as early as 1892. In 1934, Goodyear introduces the Lifeguard safety inner tube that was designed to deflate progressively instead of "blowing out". After several attempts and experiments, Goodyear introduced the SST, the tire industry's first "self-supporting" tire, in 1978.
Italian tire manufacturer Pirelli teamed up with Goodyear in 1983 to show a special asymmetrical wheel designed to lock the bead in. The same principle was applied soon after to Dunlop's Denloc ultra high performance run-flat tires, created for Porsche's 959 supercar. The Denloc design was also used in endurance racing but required unique wheels that made its run-flat capability very costly.
In parallel, Michelin created the "Bib Mousse", a foam plastic insert that lets the tire roll on spite of pressure loss. It is still widely used on car and motorcycle racers in events such as the famous Paris-Dakar rally. World Rally Championship cars also use "mousse" tires on some events, but their use and effectiveness are limited, since the foam heats up quickly and degrades at sustained high speeds.
"Run-Flat" Pioneers
The first "run-flat" tire available on a regular production vehicle was offered as an option on the 1994 Chevrolet Corvette. Goodyear's EMT tires then came standard with the fifth generation Corvette, introduced as a 1997 model, an industry first. This design uses reinforced sidewalls that enable the tire to support its share of vehicle weight without collapsing measurably. The tires can be mounted on standard wheels.
Then, in 1996, radial tire pioneer Michelin unveiled a different principle that centered on a solid inner wheel "insert" on which a pressure-less tire could run safely for some distance. A year later, the French manufacturer revealed its Pneu ? accrochage vertical or PAV, which can be translated as "Vertical Anchorage Tire" for the way the tire bead "seats onto the rim vertically." The new concept made run-flat capability possible without having to contend with a large performance compromise.
The original acronym PAV was changed to PAX in 1998: "because of its universality—and for the values of peace of mind, safety and the future that it conveys."
The key elements of Michelin's PAX system are special wheels with unique tire bead locks and a solid insert that can fully support its share of the vehicle's weight and let it continue rolling even without any tire pressure.
Early PAX designs used a support ring made of rubber, but more recent versions and those in lighter-duty vehicles use a "magic ring" that combines polyurethane and rubber, the main benefit being reduced unsprung weight. And a pressure warning system is fitted, of course.
Global Joint Ventures
Michelin has since then struck alliances with major rivals Goodyear, Pirelli and Sumitomo to develop new tires and wheels around this new design in order to make it the universal standard. At the 2002 Geneva show, all three presented new run-flat tires all based on the PAX system.
The two giants of the tire industry stated: "Goodyear and Michelin are convinced, after an analysis of other tire/wheel combinations, that the PAX system is the best platform for incorporation of future tire concepts into new vehicle designs."
Both manufacturers have also worked on tires that could equip the much-publicized, ultra-frugal PNGV car project mandated by the U.S. Government. Innovative Italian manufacturer Pirelli has also joined in and announced that it was developing run-flat tires in conformity with the principles of the PAX system.
Another joint project was made public in January 2002. Bridgestone Corporation then announced that it had formed an alliance with German maker Continental AG to develop run-flat tire technology. Bridgestone agreed to share knowledge related to its SSR tires while Continental would bring its Conti Safety Ring (CSR) technology to the table.
Technology and Regulation Evolving Quickly
Modern sports cars use very low aspect ratio tires (tread width divided by sidewall height) and ride comfort is not as big a concern on these as on other vehicles. A wide tread and low sidewalls generate maximum traction and responsiveness. A short sidewall is also easier to reinforce and flexes much less to begin with.
This made the Corvette a natural choice to pioneer run-flat tires as an option on 1995 models. Several sports cars have followed suit, running on tires made by all the major manufacturers.
Because the vehicle's actual handling changes so little, the driver needs to be informed of any significant loss of pressure. Pressure monitors have always been essential with this type of tire, but they will soon become mandatory.
Carmakers will effectively need to install such systems in all new production vehicles to comply with new rules stipulated by the National Highway Transportation Agency's (NHTSA) Transportation Recall Enhancement, Accountability and Documentation (or TREAD) Act.
These new regulations will mandate low pressure warning systems for all 2004 model year vehicles, among other measures. The act was, in part, a reaction to numerous tire failures involving sport-utility vehicles that were reported in recent years.
Because of this, more run-flat tires will invariably be fitted at the factory. Many luxury and performance models will get them standard, but family-oriented vehicles such as the all-new 2004 Toyota Sienna AWD is already equipped with true run-flat tires also.
Much research and development work is being done on highly-automated, ultra-precise systems to manufacture run-flat tires, notably those which are designed from the PAX system. Because of the specially-designed wheels they use, these also require specific installation techniques and tire-changing machines.
Numerous Benefits
With run-flat tires, there is no need for a spare wheel or a car jack, for that matter. This frees up space for luggage, lowers cost and saves some weight, which makes for a small gain in fuel economy.
Several high-visibility models such as BMW's Z4 and Z8 sports cars, the aforementioned Chevrolet Corvette, the Lexus SC 430, the MINI Cooper and Cooper S, and the spectacular new Rolls-Royce Phantom are all equipped with run-flat-type tires. These have been engineered specifically in cooperation between the car and tire manufacturer along the vehicle's development process.
Some "run-flat" tires are currently available as replacement units. But they are generally more rigid, heavier and more expensive than conventional designs of the same size, especially when you factor in the cost of a pressure-monitoring system.
Run-flat tires can also substantially affect ride comfort and the durability of some vehicle components in real-world driving. Suspension parts, most notably. Ideally, a vehicle's structure and suspension components should be designed for the very different nature and characteristics of run-flat tires, and vice-versa.
A New Age Coming
According to experts, all road-going production vehicles will eventually come standard with run-flat-type tires. The rules on mandatory tire pressure monitors for all 2004 model year vehicles, brought about by the TREAD Act, will trigger substantial growth in run-flat tire installation at the factory. Such a development meshes perfectly with manufacturers' intention to eliminate the spare wheel and all related paraphernalia from their vehicles.
As OEM installation rates increase dramatically, so will the availability or fully-adapted replacement units. The cost of which should follow the reverse trend.
All this is excellent news for all of us, drivers and passengers alike. A new driving safety paradigm is coming soon, thanks to emerging and interconnected tire technologies. It's a thankless job, being round and black, but tires will indeed keep the world turning for a long time still.
Current production vehicles equipped with run-flat tires:
Audi A8 (PAX)
BMW 3-Series *
BMW Z4
BMW Z8
Cadillac CTS-V
Cadillac XLR
Chevrolet Corvette
Dodge Viper SRT-10
Hummer H1*
Lexus SC 430
MINI Cooper*
MINI Cooper S
Rolls-Royce Phantom (PAX)
Toyota Sienna AWD (2004)
. Run Flats are seen as the future. As cars need the trunk space and weight savings of no spare. THey are not perfect but EVERY car maker is going towards this way. With a GS hybrid coming, those batteries have to stow somewhere as well. The new Chevy Z06 uses them., the BMW Z4, the BMW 5 to name a few.http://autos.msn.com/advice/article....21164&src=News
Run-Flat Tires:
A New Standard Rising Click Here!
2003 Chevrolet Corvette Coupe The Chevrolet Corvette celebrates its 50th anniversary in 2003 but also its 10th model year as run-flat tire pioneer.
by Editors of MSN Autos Canada / U.S.
In a few years, accidents due to tire blowouts should become a thing of the past, along with spare wheels and cumbersome jacks.
2004 Toyota Sienna
The new 2004 Toyota Sienna AWD minivan is the first mainstream, family-oriented vehicle to benefit from the undeniable safety of standard run-flat-type tires.
PAX
This cutaway photo of a tire using the Michelin-developed PAX system clearly shows the solid "ring" that supports the tire tread in the event of a pressure loss.
advertisement
Gentex pressure monitor
Air pressure monitors are mandatory with run-flat tires. One such product is a new Gentex mirror-mounted display.
BMW Z8
With wide tires, big wheels and a small trunk, BMW's exotic Z8 sports car is a natural for run-flat performance tires as standard fitment from day one.
Michelin PAX system
The key elements of Michelin's PAX system are special wheels with tire bead locks and a solid "insert" that can support its share of vehicle weight.
Magic Ring
If this same tire loses inflation pressure, its sidewalls flex and the PAX syst***s polyurethane/rubber "magic ring" enables the vehicle to keep rolling.
Goodyear F1 Steel
Goodyear's F1 Steel tire was the first run-flat tire offered as standard fitment on a production model, the fifth generation Corvette, in 1997.
Mini Cooper S
The 2003 MINI Cooper S comes standard with 16-inch, all-season run-flat tires or these optional 17-inch performance run-flats on Minilite-replica alloy wheels.
When J.D. Power and Associates asked thousands what they most wanted in a new vehicle for a 2001 study, 87 per cent of respondents said: run-flat tires, making these the most desirable feature by far.
These so-called run-flat, extended mobility, continuous mobility or zero-pressure tires can be driven at normal speeds, for some distance, without any air pressure in the event of a puncture, a deep cut or the ravages of just about any other road hazard.
By contrast, "self-sealing" tires use different methods to preserve inflation, but there is a definite limit to the severity of the damage they can incur. These tires simply cannot be driven without any inflation pressure.
In the Name of Safety
The original idea of an "anti-puncture" tire appeared in a patent request as early as 1892. In 1934, Goodyear introduces the Lifeguard safety inner tube that was designed to deflate progressively instead of "blowing out". After several attempts and experiments, Goodyear introduced the SST, the tire industry's first "self-supporting" tire, in 1978.
Italian tire manufacturer Pirelli teamed up with Goodyear in 1983 to show a special asymmetrical wheel designed to lock the bead in. The same principle was applied soon after to Dunlop's Denloc ultra high performance run-flat tires, created for Porsche's 959 supercar. The Denloc design was also used in endurance racing but required unique wheels that made its run-flat capability very costly.
In parallel, Michelin created the "Bib Mousse", a foam plastic insert that lets the tire roll on spite of pressure loss. It is still widely used on car and motorcycle racers in events such as the famous Paris-Dakar rally. World Rally Championship cars also use "mousse" tires on some events, but their use and effectiveness are limited, since the foam heats up quickly and degrades at sustained high speeds.
"Run-Flat" Pioneers
The first "run-flat" tire available on a regular production vehicle was offered as an option on the 1994 Chevrolet Corvette. Goodyear's EMT tires then came standard with the fifth generation Corvette, introduced as a 1997 model, an industry first. This design uses reinforced sidewalls that enable the tire to support its share of vehicle weight without collapsing measurably. The tires can be mounted on standard wheels.
Then, in 1996, radial tire pioneer Michelin unveiled a different principle that centered on a solid inner wheel "insert" on which a pressure-less tire could run safely for some distance. A year later, the French manufacturer revealed its Pneu ? accrochage vertical or PAV, which can be translated as "Vertical Anchorage Tire" for the way the tire bead "seats onto the rim vertically." The new concept made run-flat capability possible without having to contend with a large performance compromise.
The original acronym PAV was changed to PAX in 1998: "because of its universality—and for the values of peace of mind, safety and the future that it conveys."
The key elements of Michelin's PAX system are special wheels with unique tire bead locks and a solid insert that can fully support its share of the vehicle's weight and let it continue rolling even without any tire pressure.
Early PAX designs used a support ring made of rubber, but more recent versions and those in lighter-duty vehicles use a "magic ring" that combines polyurethane and rubber, the main benefit being reduced unsprung weight. And a pressure warning system is fitted, of course.
Global Joint Ventures
Michelin has since then struck alliances with major rivals Goodyear, Pirelli and Sumitomo to develop new tires and wheels around this new design in order to make it the universal standard. At the 2002 Geneva show, all three presented new run-flat tires all based on the PAX system.
The two giants of the tire industry stated: "Goodyear and Michelin are convinced, after an analysis of other tire/wheel combinations, that the PAX system is the best platform for incorporation of future tire concepts into new vehicle designs."
Both manufacturers have also worked on tires that could equip the much-publicized, ultra-frugal PNGV car project mandated by the U.S. Government. Innovative Italian manufacturer Pirelli has also joined in and announced that it was developing run-flat tires in conformity with the principles of the PAX system.
Another joint project was made public in January 2002. Bridgestone Corporation then announced that it had formed an alliance with German maker Continental AG to develop run-flat tire technology. Bridgestone agreed to share knowledge related to its SSR tires while Continental would bring its Conti Safety Ring (CSR) technology to the table.
Technology and Regulation Evolving Quickly
Modern sports cars use very low aspect ratio tires (tread width divided by sidewall height) and ride comfort is not as big a concern on these as on other vehicles. A wide tread and low sidewalls generate maximum traction and responsiveness. A short sidewall is also easier to reinforce and flexes much less to begin with.
This made the Corvette a natural choice to pioneer run-flat tires as an option on 1995 models. Several sports cars have followed suit, running on tires made by all the major manufacturers.
Because the vehicle's actual handling changes so little, the driver needs to be informed of any significant loss of pressure. Pressure monitors have always been essential with this type of tire, but they will soon become mandatory.
Carmakers will effectively need to install such systems in all new production vehicles to comply with new rules stipulated by the National Highway Transportation Agency's (NHTSA) Transportation Recall Enhancement, Accountability and Documentation (or TREAD) Act.
These new regulations will mandate low pressure warning systems for all 2004 model year vehicles, among other measures. The act was, in part, a reaction to numerous tire failures involving sport-utility vehicles that were reported in recent years.
Because of this, more run-flat tires will invariably be fitted at the factory. Many luxury and performance models will get them standard, but family-oriented vehicles such as the all-new 2004 Toyota Sienna AWD is already equipped with true run-flat tires also.
Much research and development work is being done on highly-automated, ultra-precise systems to manufacture run-flat tires, notably those which are designed from the PAX system. Because of the specially-designed wheels they use, these also require specific installation techniques and tire-changing machines.
Numerous Benefits
With run-flat tires, there is no need for a spare wheel or a car jack, for that matter. This frees up space for luggage, lowers cost and saves some weight, which makes for a small gain in fuel economy.
Several high-visibility models such as BMW's Z4 and Z8 sports cars, the aforementioned Chevrolet Corvette, the Lexus SC 430, the MINI Cooper and Cooper S, and the spectacular new Rolls-Royce Phantom are all equipped with run-flat-type tires. These have been engineered specifically in cooperation between the car and tire manufacturer along the vehicle's development process.
Some "run-flat" tires are currently available as replacement units. But they are generally more rigid, heavier and more expensive than conventional designs of the same size, especially when you factor in the cost of a pressure-monitoring system.
Run-flat tires can also substantially affect ride comfort and the durability of some vehicle components in real-world driving. Suspension parts, most notably. Ideally, a vehicle's structure and suspension components should be designed for the very different nature and characteristics of run-flat tires, and vice-versa.
A New Age Coming
According to experts, all road-going production vehicles will eventually come standard with run-flat-type tires. The rules on mandatory tire pressure monitors for all 2004 model year vehicles, brought about by the TREAD Act, will trigger substantial growth in run-flat tire installation at the factory. Such a development meshes perfectly with manufacturers' intention to eliminate the spare wheel and all related paraphernalia from their vehicles.
As OEM installation rates increase dramatically, so will the availability or fully-adapted replacement units. The cost of which should follow the reverse trend.
All this is excellent news for all of us, drivers and passengers alike. A new driving safety paradigm is coming soon, thanks to emerging and interconnected tire technologies. It's a thankless job, being round and black, but tires will indeed keep the world turning for a long time still.
Current production vehicles equipped with run-flat tires:
Audi A8 (PAX)
BMW 3-Series *
BMW Z4
BMW Z8
Cadillac CTS-V
Cadillac XLR
Chevrolet Corvette
Dodge Viper SRT-10
Hummer H1*
Lexus SC 430
MINI Cooper*
MINI Cooper S
Rolls-Royce Phantom (PAX)
Toyota Sienna AWD (2004)
Last edited by LexFather; 03-04-05 at 09:12 PM.
03-06-05, 11:41 PM
#19
Lexus Test Driver
Sick, you amaze me...
As far as Lexus is concerned, Run flats are regional. The Central and Eastern Regions get them. The South and West get conventional tires. I have driven nothing but run flats but I don't notice them much like I did on the SC430's. On SC's I strongly advocate replacing the RF's as soon as they are worn. I would theorize that the conventional tires would have a more compliant ride as the sidewalls are not as stiff. Sorry I missed this thread and stumbled onto it just today.
03-07-05, 02:41 AM
#20
Lexus Test Driver
Back to the topic of ride. Just picked up my GS430 on Saturday in Virginia. Drove it around town and then back home via I95 to Connecticut.
The ride is pretty stiff, but the factory always ships the vehicles with 50-60lbs of pressure in them. Many times the dealers forget to reduce the pressure. Frequently if they do, they still leave it at 38lbs +. I need to check the pressure on the tires, I always like to set them at around 32-34. This might make a difference.
Before you all freak, check the tire pressure. I always pickup a new vehicle with at least 6lbs too much pressure in them.
The ride is pretty stiff, but the factory always ships the vehicles with 50-60lbs of pressure in them. Many times the dealers forget to reduce the pressure. Frequently if they do, they still leave it at 38lbs +. I need to check the pressure on the tires, I always like to set them at around 32-34. This might make a difference.
Before you all freak, check the tire pressure. I always pickup a new vehicle with at least 6lbs too much pressure in them.
03-07-05, 05:20 AM
#21
Lexus Test Driver
Very good advice by Looknow
I constantly find that techs like to leave a cushion of 5-8 pounds of additional pressure. I usually carry a tire pressure gauge around with me and it does make a huge difference if the RF's are overinflated. 33 PSI is perfect. If you do bleed the pressures make sure all of the tires are the same because of the tire pressure monitoring system. Sometimes a cold snap will set off the monitor. Get a trusty gauge folks....
03-07-05, 06:58 AM
#22
Lexus Champion
The run flats may come on many of the vehicles, but they are listed under "optional equipment" on Lexus.com, in the brochure, etc etc.
I'll special order if necessary to avoid them. And the brochure no longer mentions a "full size spare on alloy wheel" as it does with my 01 430. So I guess our spare (with the standard tires) is a can of sealer.................
I'll special order if necessary to avoid them. And the brochure no longer mentions a "full size spare on alloy wheel" as it does with my 01 430. So I guess our spare (with the standard tires) is a can of sealer.................
03-07-05, 08:33 AM
#23
Lexus Test Driver
You are safe in the South from the dreaded runflats
I really don't have anything to compare them to so it's hard to say what the differences are. I'm going to swap out some RF's on a GS430 for conventionals and then I'll post my impressions. The spare will be a temporary type in the South. I don't believe there is enough room for a full size in the spare compartment.
03-07-05, 08:36 AM
#24
Lexus Connoisseur
Originally Posted by Rockville
I really don't have anything to compare them to so it's hard to say what the differences are. I'm going to swap out some RF's on a GS430 for conventionals and then I'll post my impressions. The spare will be a temporary type in the South. I don't believe there is enough room for a full size in the spare compartment.
03-07-05, 09:24 AM
#25
Lexus Test Driver
Originally Posted by mooretorque
The run flats may come on many of the vehicles, but they are listed under "optional equipment" on Lexus.com, in the brochure, etc etc.
I'll special order if necessary to avoid them. And the brochure no longer mentions a "full size spare on alloy wheel" as it does with my 01 430. So I guess our spare (with the standard tires) is a can of sealer.................
I'll special order if necessary to avoid them. And the brochure no longer mentions a "full size spare on alloy wheel" as it does with my 01 430. So I guess our spare (with the standard tires) is a can of sealer.................
Also, no matter how you slice it, you're gonna get dirty changing the tires. Jump into your finely appointed Lexus with wheel grease and grime, yikes.
I prefer progress. Run flats are the way to go IMO. But the price needs to come down a bit. I purchased the warranty for the rims and tires. $450 cause I know somethings gonna go wrong. The dealer lady told me if you scratch the rim it doesn't cover it so find a pot hole and bend the rim :-)
03-07-05, 09:47 AM
#26
Lexus Champion
Progress is inevitable. We're talking about no longer worrying about being stranded on the side of the road. I for one would rather my wife can drive to a safe gas station on the flat tire than have to try to pull a tire out of the trunk and change it.
03-07-05, 12:15 PM
#27
Lexus Fanatic
Originally Posted by flipside909
Highways in the South specifically Florida they are rough. Fact or myth, the asphalt composite is made w/seashells?
we don't have many potholes though and all roads aren't like this.
03-07-05, 01:19 PM
#28
Guest
Posts: n/a
Originally Posted by Rockville
As far as Lexus is concerned, Run flats are regional. The Central and Eastern Regions get them. The South and West get conventional tires. I have driven nothing but run flats but I don't notice them much like I did on the SC430's. On SC's I strongly advocate replacing the RF's as soon as they are worn. I would theorize that the conventional tires would have a more compliant ride as the sidewalls are not as stiff. Sorry I missed this thread and stumbled onto it just today.
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