Speed Volume option on radio
#21
01-05-2007, 10:41 AM
Re: Speed Volume option on radio
Correct again! They refer to it as "stagger". I believe it had a more pronounced on the handling back in the bias ply days. It may still come into play on the radials used in Nascar today...although to a somewhat lesser degree than with bias ply tires. But please don't quote me on this since I don't follow Nascar and I also don't claim to be a tire expert.
#22
01-05-2007, 12:48 PM
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Re: Speed Volume option on radio
You guys are not comparing apples to apples.
Go out and try it! With the Ford Escape Hybrid and most ( if not all ) passenger road tires, the distance traveled per revolution DOES NOT CHANGE with normal changes in air pressure.
Making annalogies to "special case" and "special applications" does not apply.
The height of your vehicle will change with air pressure, but the distance traveled remains the same. I'll send $1000 to the first person that can prove otherwise with normal, modern, passenger car tires!
Go out and try it! With the Ford Escape Hybrid and most ( if not all ) passenger road tires, the distance traveled per revolution DOES NOT CHANGE with normal changes in air pressure.
Making annalogies to "special case" and "special applications" does not apply.
The height of your vehicle will change with air pressure, but the distance traveled remains the same. I'll send $1000 to the first person that can prove otherwise with normal, modern, passenger car tires!
Last edited by gpsman1; 01-05-2007 at 01:39 PM. Reason: spelling
#23
01-05-2007, 12:59 PM
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Re: Speed Volume option on radio
Again, not comparing apples to apples.
The system of using ABS to "indirectly" measure tire pressure status will only tell you when there is a gross change in tire shape. The only thing this method is good for is telling you when your tire is FLAT. And if you need a sensor for that, then you are an idiot.
The tire circumference on modern passenger tires changes by less than 1mm ( out of more than 2000mm ) at any pressures between 10psi and 60psi. So in theory, the tire size changes. In reality, the change is too small to measure, or to have any mentionable effect on speedometers or odometers. I didn't know you guys wanted to talk "microns". If that's the case, then the length of your vehicle changes with speed also, as Einstein predicted, as the atoms get spread out by 0.00000000000000001mm when you travel fast... Geez... can we come back to what actually matters now?
Again, don't take my word for it. GO OUT AND MEASURE!
-John
The system of using ABS to "indirectly" measure tire pressure status will only tell you when there is a gross change in tire shape. The only thing this method is good for is telling you when your tire is FLAT. And if you need a sensor for that, then you are an idiot.
The tire circumference on modern passenger tires changes by less than 1mm ( out of more than 2000mm ) at any pressures between 10psi and 60psi. So in theory, the tire size changes. In reality, the change is too small to measure, or to have any mentionable effect on speedometers or odometers. I didn't know you guys wanted to talk "microns". If that's the case, then the length of your vehicle changes with speed also, as Einstein predicted, as the atoms get spread out by 0.00000000000000001mm when you travel fast... Geez... can we come back to what actually matters now?
Again, don't take my word for it. GO OUT AND MEASURE!
-John
If this is indeed true, then how do many manufacturers (including some Ford models) utilize the ABS sensors instead of actual air pressure sensors to operate their TPMS systems?
For example, this was taken from from the 2002 Windstar shop manual section 204-04:
"The Low Tire Warning (LTW) system detects differences in inflation pressures in one or more tires. The system uses the ABS wheel speed sensors to monitor the rolling radius of the wheel and tire assemblies."
A few other vehicles that use this approach include 2001 to 2003 Ford Windstar, 1997-2002 Buick Park Avenue, 1999-2003 Buick Century & Regal, 2002-2003 Buick LeSabre, 2003 Buick Rendezvous & Aztek, 2000-2003 Chevy Impala & Monte Carlo, 1999-2002 Chevy Alero, 1999-2002 Pontiac Grand Am, 1997 - 2003 Pontiac Grand Prix, 2000 - 2003 Pontiac Bonneville, and 2001-2003 Oldsmobile Aurora. Source: http://www.aa1car.com/library/tire_monitors.htm
For example, this was taken from from the 2002 Windstar shop manual section 204-04:
"The Low Tire Warning (LTW) system detects differences in inflation pressures in one or more tires. The system uses the ABS wheel speed sensors to monitor the rolling radius of the wheel and tire assemblies."
A few other vehicles that use this approach include 2001 to 2003 Ford Windstar, 1997-2002 Buick Park Avenue, 1999-2003 Buick Century & Regal, 2002-2003 Buick LeSabre, 2003 Buick Rendezvous & Aztek, 2000-2003 Chevy Impala & Monte Carlo, 1999-2002 Chevy Alero, 1999-2002 Pontiac Grand Am, 1997 - 2003 Pontiac Grand Prix, 2000 - 2003 Pontiac Bonneville, and 2001-2003 Oldsmobile Aurora. Source: http://www.aa1car.com/library/tire_monitors.htm
Last edited by gpsman1; 01-05-2007 at 02:38 PM. Reason: spelling
#24
01-05-2007, 01:20 PM
Re: Speed Volume option on radio
Again, not comparing apples to apples.
The system of using ABS to "indirectly" measure tire pressure status will only tell you when there is a gross change in tire shape. The only thing this method is good for is telling you when your tire is FLAT. And if you need a sensor for that, then you are an idiot.
The tire diameter on modern passenger tires changes by less than 1mm ( out of more than 2000mm ) at any pressures between 10psi and 60psi.
Again, don't take my word for it. GO OUT AND MEASURE!
-John
The system of using ABS to "indirectly" measure tire pressure status will only tell you when there is a gross change in tire shape. The only thing this method is good for is telling you when your tire is FLAT. And if you need a sensor for that, then you are an idiot.
The tire diameter on modern passenger tires changes by less than 1mm ( out of more than 2000mm ) at any pressures between 10psi and 60psi.
Again, don't take my word for it. GO OUT AND MEASURE!
-John
http://www.gm.com/company/gmability/...m/sensing.html
it triggers at 10psi lower than normal.... thats when it triggers, not necesarily what it can measure. So its at least capable of seeing a tire thats 10psi low but is probably a bit better than that. Thats not highly accurate BUT its FAR from FLAT. Many people are raising theirs by 10psi or more.
Theres a little demo of what too little air looks like on a tire at
http://www.safercar.gov/Tires/pages/...adingCheck.htm
You have to go pretty low to say its "flat".
Looking at that last link... and dropping the pressure to 50%.... (more than 10PSI) the tire looks down a bit but you wouldn't have to be an IDIOT to think it was okay. At 70% it would be down more than 10PSI... looks pretty decent at that level. I guess I'm an idiot.
Oh... whats with the need to YELL
It was categorically denied that there was ANY change in tire diameter. All thats been pointed out is that statement is NOT true, there is a small change. And apprently it IS actually measureable at changes in pressure levels of 10PSI and maybe less.
Relax a bit... it's just a discussion.
I wasn't saying it was HUGE or anything myself. I just thought there should be a difference and wondered aloud how significant it would be.
Last edited by TeeSter; 01-05-2007 at 01:31 PM.
#25
01-05-2007, 01:42 PM
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Re: Speed Volume option on radio
They do this for stability reasons. Tire pressure changes the height of the car on one side, making it more stable on banked curves. I suspect they only do this on oval or circular tracks! 
They also have "specialty" tires, unlike the ones on the FEH.
They also have "specialty" tires, unlike the ones on the FEH.Last edited by gpsman1; 01-05-2007 at 01:50 PM.
#26
01-05-2007, 02:11 PM
Re: Speed Volume option on radio
2) You're asking everyone else to "prove otherwise". TeeSter and I have both providing sources of our information, but you've yet to tell anyone where you're getting your "facts" from. Please feel free to share them with us.
3) TeeSter, I hope you spend your $1,000 gift wisely.
Last edited by Thegreatescape; 01-05-2007 at 02:15 PM.
#27
01-05-2007, 02:36 PM
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Re: Speed Volume option on radio
#1 No, it is due to the fact that the tire with lower pressure has a larger contact patch with the ground, more square inches on the ground, and more grip with the road surface, so it can pull harder. Circumference stays the same, to within 1mm or less. ( unless you have some really cheap tires, perhaps )
#2 Real world experience, plus 2 science degrees and 1 engineering degree. Passenger road tires are just too stiff to stretch like you seem to think they do.
#3 I BEG you to go out and measure the circumference of a tire on your FEH with 20psi and 40psi, before posting further. I promise they will be the same to less than 1mm.
Can anyone, an administrator perhaps, copy and paste the tire messages only to a new thread? It appears we have gotten terribly off topic of the thread title.
#2 Real world experience, plus 2 science degrees and 1 engineering degree. Passenger road tires are just too stiff to stretch like you seem to think they do.
#3 I BEG you to go out and measure the circumference of a tire on your FEH with 20psi and 40psi, before posting further. I promise they will be the same to less than 1mm.
Can anyone, an administrator perhaps, copy and paste the tire messages only to a new thread? It appears we have gotten terribly off topic of the thread title.
1) Drive a real 4WD truck with a locking front axle with only a 5 psi variance between the front tires and you'll notice a very definite pull to the side with the lower pressure. This is due to the reduced dynamic circumference of the tire with no differential action to compensate for it. If you unlock the hubs the pull will be gone. A difference in height would not be affected by switching from a locked (no differential action) axle to a fully open one.
2) You're asking everyone else to "prove otherwise". TeeSter and I have both providing sources of our information, but you've yet to tell anyone where you're getting your "facts" from. Please feel free to share them with us.
2) You're asking everyone else to "prove otherwise". TeeSter and I have both providing sources of our information, but you've yet to tell anyone where you're getting your "facts" from. Please feel free to share them with us.
Last edited by gpsman1; 01-05-2007 at 02:55 PM.
#28
01-05-2007, 03:31 PM
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Re: Speed Volume option on radio
Real world, actual data, measured with stock Continental EcoPlus tires that came as standard equipment on a 2005 Ford Escape Hybrid.
>At 50 psi Tire Circumference = 2100 mm or 82.66 inches
>At 35 psi Tire Circumference = 2100 mm or 82.66 inches
>At 25 psi Tire Circumference = 2100 mm or 82.66 inches
>At 20 psi Tire Circumference = 2099 mm or 82.64 inches
>At 15 psi Tire Circumference = 2098 mm or 82.60 inches
The following is a description of the contact patch:
>Contact patch at 50 psi = 11,000 sq.mm or about 18 sq.in.
>Contact patch at 35 psi = 16,000 sq.mm or about 25 sq.in.
>Contact patch at 15 psi = 38,500 sq.mm or about 60 sq.in.
Ok, at 50psi, we travel 82.66 inches per revolution.
After 1 million revolutions, we will travel 1304.60 miles.
At 20psi ( probably unsafe ) we will travel 1304.30 miles after those same, 1 million revolutions.
Since most people drive in the 25psi to 50psi ranges, there is NO over/under reporting on the speedometer or odometer.
-John
>At 50 psi Tire Circumference = 2100 mm or 82.66 inches
>At 35 psi Tire Circumference = 2100 mm or 82.66 inches
>At 25 psi Tire Circumference = 2100 mm or 82.66 inches
>At 20 psi Tire Circumference = 2099 mm or 82.64 inches
>At 15 psi Tire Circumference = 2098 mm or 82.60 inches
The following is a description of the contact patch:
>Contact patch at 50 psi = 11,000 sq.mm or about 18 sq.in.
>Contact patch at 35 psi = 16,000 sq.mm or about 25 sq.in.
>Contact patch at 15 psi = 38,500 sq.mm or about 60 sq.in.
Ok, at 50psi, we travel 82.66 inches per revolution.
After 1 million revolutions, we will travel 1304.60 miles.
At 20psi ( probably unsafe ) we will travel 1304.30 miles after those same, 1 million revolutions.
Since most people drive in the 25psi to 50psi ranges, there is NO over/under reporting on the speedometer or odometer.
-John
#29
01-05-2007, 05:28 PM
Re: Speed Volume option on radio
Whoa!
Let cool heads prevail, please. I know that this forum has some great knowledgeable contributors. Let's not digress and keep to the conversation so we can get the best out of the technology we "all" chose.
I will be investigating the Speed Volume that this thread was originally started. I see that there may be another need for a Odometer Accuracy thread. If so, then please start one. As a new contributor, if we can keep to the subject, this will be a great source of information for anyone who has deemed the FEH as a superior choice (not to knock others as they seem to have some good ideas
).
IMHO, I have seen some great forums shot to heck and become unusable because of this.
-R
Let cool heads prevail, please. I know that this forum has some great knowledgeable contributors. Let's not digress and keep to the conversation so we can get the best out of the technology we "all" chose.
I will be investigating the Speed Volume that this thread was originally started. I see that there may be another need for a Odometer Accuracy thread. If so, then please start one. As a new contributor, if we can keep to the subject, this will be a great source of information for anyone who has deemed the FEH as a superior choice (not to knock others as they seem to have some good ideas
).IMHO, I have seen some great forums shot to heck and become unusable because of this.
-R
#30
01-06-2007, 07:58 AM
Re: Speed Volume option on radio
Unfortunately, all of these static measurements fail to address how an ABS sensor can be used to determine the difference in dynamic tire diameter and circumference to infer a change in air pressure. The only way this can be accomplished is if the tires are turning at different speeds. When travelling straight, this means their effective diameters/circumferences are clearly different. Or am I missing somthing obvious here?
Sorry, but tire pressure clearly does affect the effective diameter and circumference of a tire. "Real world experience, plus 2 science degrees and 1 engineering degree" does not mean you're always right. Can you possibly provide a single unbiased outside source of data to support your position? (Even Einstein was wrong at times.)
Sorry, but tire pressure clearly does affect the effective diameter and circumference of a tire. "Real world experience, plus 2 science degrees and 1 engineering degree" does not mean you're always right. Can you possibly provide a single unbiased outside source of data to support your position? (Even Einstein was wrong at times.)
