Psi thread. Please read..... Stop this tpms thread already.
#1
10-28-2008, 01:54 PM
Psi thread. Please read..... Stop this tpms thread already.
SO i have been seeing so many TPMS thread whats the recommended PSI.
to some people they like to put 40 for bette mileage. PLEASE READ ON
1. Higher PSI in tires will make tires rounder just think.. roll a fully inflated ball vs a partially deflated ball (yes you will get a little more MPG.
2. Autocrossers love to run 40+PSI.. reason is because it gives them much quicker steering response due to less tirelean. Straight line draggers love 14-20psi because the tire grips better and they dont need side steering responsiveness (They have a purpose)
For the regular economy street specs most places recommends anywhere from 30-34psi.. with 33PSI being ideal.. Most of the guys here like to run a little on the higher side because we love the steering responsiveness. (but not so safe)
I run 33psi all around.
it is not recommended to run 40psi all the time.. it tends to create stress cracks all over the tires over time.. and running below 30psi will wear out tires prematurely
ky-high gasoline prices have people looking for various ways to squeeze more miles out of every gallon.
But be careful. There are a lot of bogus advice going around. For instance, the suggestion that you should over-inflate your tires all the way up to the maximum load listed on the side wall is not a good idea.
Yes, over-inflation will reduce rolling resistance, which might boost your mileage ever so slightly. But that's just part of the story.
"Your tires will wear out quicker and you're going to pay for it on the backside with replacing your tires sooner," said Dave Armstrong with AAA Washington.
Over-inflation reduces the tire's footprint - the rubber on the road - which increases stopping distance and negatively impacts cornering.
"Also in the wet, you're going to skid a lot easier if you have to slam the brakes on in a panic stop," Armstrong said.
Over-inflation can also be dangerous.
"If you've over-inflated your tires and overloaded your car, it's going to put a lot of stress on those tires and a blow-out is definitely a potential bad side effect," Armstrong told me.
So play it smart. Keep your tires properly inflated. Follow the recommendations from the manufacturer.
1. Higher Psi reduces the rolling resistance of the tire, so yes you get better gas mileage. However with tires there is always compromises. Higher psi makes you more susceptible to impact breaks. A blow out and high speeds could be fatal if you can't handle it properly.
2. Max inflation pressure on the sidewall is also for maximum load. If you aren't running the maximum load there's no point in running that inflation pressure. Inflation pressure is based on the load to the tire. If you're running OE sizes then run the OE pressures. Upsizing there are formulas you use to calculate the new pressures.
Running tires at the optimum pressure, based on load is ideal, as the stresses on the casing are optimum. This will ensure that life of the casing of the tire. Overinflation will cause premature center tread wear. In case of overinflation the profile of the tire becomes round instead of flat.
The only thing that really matters is OPERATING TEMP, which may varry depending on how your driving as well as the type of tire. Some tires like the Azenis RT615 are made to get hot as fast as possible to do well in AutoX where they run short courses that provide no warm-up time. Other tires may be designed for racing circuit where overheating is perhaps an issue and they'll be designed to shed heat as much as possible.
Since we can't easily measure Operating temp unless you have a laser heat gun etc. ( I do ) then the best way is to measure your cold temp for regular driving. This is of course expected to raise a few psi under operation and create the optimal performance conditions.
In general, over-inflation will make the tire balloon and swell in the center which means the middle of your tire will show wear prematurely and will make the contact patch pressures uneven meaning they will not grip as well. The 2nd thing it will do is make the ride harsh and lower it into the break-away zone of the tires 100% traction threshold. Higher psi usually means higher MPG because the lack of flex equates to less rolling resistance.
Under-inflation will do the opposite of the balloon effect. You'll find the outside parts of the tire will wear prematurely. They sidewalls may even become damaged as they roll over and give way to the car's lateral forces since they are unable to support the weight. In general your performance spec tires will be better about this as the sidewalls are already very stiff. The sidewalls may end up breaking down and they may also overheat due to sidewall flex, this can potentially destroy the tire violently. You may remember the Ford Explorer that had the Firestones that EXPLODED causing a recall. That was not the tire's fault, but rather it was because Ford sent their trucks out with 25psi to make the suspension feel softer, which overheated the side-walls and made the tires burst. There will be a decrease in MPG of course since rolling resistance due to sidewall flex has increased. We all know a flat tire is damn hard to push.
There's a million other factors we could bring up but the bottom line is you should run the tire as the manufacture states. I would suggest you stay in 30psi-37 psi in general. Race setup must be correctly setup for usage every time any change is made or the location of the race is different
Bottom line is the HOT temp should end up probably around 36psi in general but your race setup is different. Fill your tires up to 33-34psi COLD if you don't know what your doing.
to some people they like to put 40 for bette mileage. PLEASE READ ON
1. Higher PSI in tires will make tires rounder just think.. roll a fully inflated ball vs a partially deflated ball (yes you will get a little more MPG.
2. Autocrossers love to run 40+PSI.. reason is because it gives them much quicker steering response due to less tirelean. Straight line draggers love 14-20psi because the tire grips better and they dont need side steering responsiveness (They have a purpose)
For the regular economy street specs most places recommends anywhere from 30-34psi.. with 33PSI being ideal.. Most of the guys here like to run a little on the higher side because we love the steering responsiveness. (but not so safe)
I run 33psi all around.
it is not recommended to run 40psi all the time.. it tends to create stress cracks all over the tires over time.. and running below 30psi will wear out tires prematurely
ky-high gasoline prices have people looking for various ways to squeeze more miles out of every gallon.
But be careful. There are a lot of bogus advice going around. For instance, the suggestion that you should over-inflate your tires all the way up to the maximum load listed on the side wall is not a good idea.
Yes, over-inflation will reduce rolling resistance, which might boost your mileage ever so slightly. But that's just part of the story.
"Your tires will wear out quicker and you're going to pay for it on the backside with replacing your tires sooner," said Dave Armstrong with AAA Washington.
Over-inflation reduces the tire's footprint - the rubber on the road - which increases stopping distance and negatively impacts cornering.
"Also in the wet, you're going to skid a lot easier if you have to slam the brakes on in a panic stop," Armstrong said.
Over-inflation can also be dangerous.
"If you've over-inflated your tires and overloaded your car, it's going to put a lot of stress on those tires and a blow-out is definitely a potential bad side effect," Armstrong told me.
So play it smart. Keep your tires properly inflated. Follow the recommendations from the manufacturer.
1. Higher Psi reduces the rolling resistance of the tire, so yes you get better gas mileage. However with tires there is always compromises. Higher psi makes you more susceptible to impact breaks. A blow out and high speeds could be fatal if you can't handle it properly.
2. Max inflation pressure on the sidewall is also for maximum load. If you aren't running the maximum load there's no point in running that inflation pressure. Inflation pressure is based on the load to the tire. If you're running OE sizes then run the OE pressures. Upsizing there are formulas you use to calculate the new pressures.
Running tires at the optimum pressure, based on load is ideal, as the stresses on the casing are optimum. This will ensure that life of the casing of the tire. Overinflation will cause premature center tread wear. In case of overinflation the profile of the tire becomes round instead of flat.
The only thing that really matters is OPERATING TEMP, which may varry depending on how your driving as well as the type of tire. Some tires like the Azenis RT615 are made to get hot as fast as possible to do well in AutoX where they run short courses that provide no warm-up time. Other tires may be designed for racing circuit where overheating is perhaps an issue and they'll be designed to shed heat as much as possible.
Since we can't easily measure Operating temp unless you have a laser heat gun etc. ( I do ) then the best way is to measure your cold temp for regular driving. This is of course expected to raise a few psi under operation and create the optimal performance conditions.
In general, over-inflation will make the tire balloon and swell in the center which means the middle of your tire will show wear prematurely and will make the contact patch pressures uneven meaning they will not grip as well. The 2nd thing it will do is make the ride harsh and lower it into the break-away zone of the tires 100% traction threshold. Higher psi usually means higher MPG because the lack of flex equates to less rolling resistance.
Under-inflation will do the opposite of the balloon effect. You'll find the outside parts of the tire will wear prematurely. They sidewalls may even become damaged as they roll over and give way to the car's lateral forces since they are unable to support the weight. In general your performance spec tires will be better about this as the sidewalls are already very stiff. The sidewalls may end up breaking down and they may also overheat due to sidewall flex, this can potentially destroy the tire violently. You may remember the Ford Explorer that had the Firestones that EXPLODED causing a recall. That was not the tire's fault, but rather it was because Ford sent their trucks out with 25psi to make the suspension feel softer, which overheated the side-walls and made the tires burst. There will be a decrease in MPG of course since rolling resistance due to sidewall flex has increased. We all know a flat tire is damn hard to push.
There's a million other factors we could bring up but the bottom line is you should run the tire as the manufacture states. I would suggest you stay in 30psi-37 psi in general. Race setup must be correctly setup for usage every time any change is made or the location of the race is different
Bottom line is the HOT temp should end up probably around 36psi in general but your race setup is different. Fill your tires up to 33-34psi COLD if you don't know what your doing.
Last edited by jdmgpw04; 10-28-2008 at 04:33 PM.
#4
10-28-2008, 02:32 PM
He is correct though. The manufacturer's suggestion is going to be as close to the best combination--safe and efficient--as possible; Honda's liability is depending on it.
#5
10-28-2008, 03:24 PM
jdmgpw, I have 40 years experience in running my tires 5 to 10 psi over for better mpg. When you have 5 or 6 cars to fill up you do little things like this to save money, and please don't tell me that it will wear out my tires, I have a million miles to prove you wrong.
#6
10-28-2008, 03:40 PM
But tire pressures can be tuned if desired to achieve different objectives. The other extreme occurs when people go overboard and go up/down 10 psi, or even higher up to the max the tire can handle. TPMS is a baby monitor because there are people who do the opposite and never check their tire pressures and don't realize when the pressures are too low.
You can do what you want - but I certainly don't want to be near those running tires at the sidewall PSI nor do I want to be near those with seriously underinflated tires. Both are just disasters waiting to happen when a tire finally blows/punctures.
#7
10-28-2008, 04:15 PM
did you even read the entire thread. i have stated that yes it will give you better mileage. i am just putting down everything, and no i am not telling you on what to do. its your car not mine do whatever you want (its your safety as well), and good for you that you are saving money by putting higher psi. I guess for me my safety comes first. if you were so concerned about getting better mileage on a car i think you just bought the wrong car.
Last edited by jdmgpw04; 10-28-2008 at 04:25 PM.
#8
10-28-2008, 09:14 PM
The manufacturer's suggestion is the best compromise - ride, handling, fuel mileage, TPMS sensors, all taken into account. If that is your definition of best combination, then yes, by all means go by the manufacturer's recommendations. They automatically assume the dumbest and widest audience possible in determining those numbers.
But tire pressures can be tuned if desired to achieve different objectives. The other extreme occurs when people go overboard and go up/down 10 psi, or even higher up to the max the tire can handle. TPMS is a baby monitor because there are people who do the opposite and never check their tire pressures and don't realize when the pressures are too low.
You can do what you want - but I certainly don't want to be near those running tires at the sidewall PSI nor do I want to be near those with seriously underinflated tires. Both are just disasters waiting to happen when a tire finally blows/punctures.
But tire pressures can be tuned if desired to achieve different objectives. The other extreme occurs when people go overboard and go up/down 10 psi, or even higher up to the max the tire can handle. TPMS is a baby monitor because there are people who do the opposite and never check their tire pressures and don't realize when the pressures are too low.
You can do what you want - but I certainly don't want to be near those running tires at the sidewall PSI nor do I want to be near those with seriously underinflated tires. Both are just disasters waiting to happen when a tire finally blows/punctures.
That is really what I meant. Best possible combination that can be achieved for the most people.
did you even read the entire thread. i have stated that yes it will give you better mileage. i am just putting down everything, and no i am not telling you on what to do. its your car not mine do whatever you want (its your safety as well), and good for you that you are saving money by putting higher psi. I guess for me my safety comes first. if you were so concerned about getting better mileage on a car i think you just bought the wrong car.
Last edited by Goodguy-Fly; 10-28-2008 at 09:16 PM.
#9
10-28-2008, 11:53 PM
Not disagreeing one bit with original post, but I wish you luck on this board.
And, I have a million miles "proving" (yep, right) that overinflating tires messes up the handling and tire wear.
And, I have a million miles "proving" (yep, right) that overinflating tires messes up the handling and tire wear.
#10
10-29-2008, 01:12 AM
You have a million miles to prove it? I have 5k miles on my Si that prove it. I ran over inflated tires for a bit. ~33 psi just looked bad in the front plus I heard about the MPG savings so I overinflated to about 40 and ran it. When I rotated my tires you could clearly see the center of the tire has less tread depth, and the outside had more tread.
Ok, math time kids. Lets say you get 2 more MPG at some insane PSI, 45 or some shit. You go from 33 average, then w/ overinflated tires you get 35 MPG.
33 MPG over 15,000 miles = 454.54 gallons or $1591 a year
35 MPG over 15,000 miles = 428.57 gallons or $1500 a year
So you save $91 a year. lol c'mon now, if you can't afford $91 a year you made a very wrong career choice in life somewhere
. Is it really worth risking a blow out running tires at the max PSI for less than a 100 bucks a year? And think about this too. If you do gain 2 MPG you gain 6% more MPG. You prob boost your tread wear a lot more than 6% so whats the real gain?
Ok, math time kids. Lets say you get 2 more MPG at some insane PSI, 45 or some shit. You go from 33 average, then w/ overinflated tires you get 35 MPG.
33 MPG over 15,000 miles = 454.54 gallons or $1591 a year
35 MPG over 15,000 miles = 428.57 gallons or $1500 a year
So you save $91 a year. lol c'mon now, if you can't afford $91 a year you made a very wrong career choice in life somewhere
. Is it really worth risking a blow out running tires at the max PSI for less than a 100 bucks a year? And think about this too. If you do gain 2 MPG you gain 6% more MPG. You prob boost your tread wear a lot more than 6% so whats the real gain?
#11
10-29-2008, 11:13 AM
Thank you for pointing this out. 
Ok, math time kids. Lets say you get 2 more MPG at some insane PSI, 45 or some shit. You go from 33 average, then w/ overinflated tires you get 35 MPG.
33 MPG over 15,000 miles = 454.54 gallons or $1591 a year
35 MPG over 15,000 miles = 428.57 gallons or $1500 a year
So you save $91 a year. lol c'mon now, if you can't afford $91 a year you made a very wrong career choice in life somewhere. Is it really worth risking a blow out running tires at the max PSI for less than a 100 bucks a year? And think about this too. If you do gain 2 MPG you gain 6% more MPG. You prob boost your tread wear a lot more than 6% so whats the real gain?
33 MPG over 15,000 miles = 454.54 gallons or $1591 a year
35 MPG over 15,000 miles = 428.57 gallons or $1500 a year
So you save $91 a year. lol c'mon now, if you can't afford $91 a year you made a very wrong career choice in life somewhere
. Is it really worth risking a blow out running tires at the max PSI for less than a 100 bucks a year? And think about this too. If you do gain 2 MPG you gain 6% more MPG. You prob boost your tread wear a lot more than 6% so whats the real gain?
#12
10-29-2008, 12:44 PM
[quote=jdmgpw04;474551]SO i have been seeing so many TPMS thread whats the recommended PSI.
There's a million other factors we could bring up but the bottom line is you should run the tire as the manufacture states. I would suggest you stay in 30psi-37 psi in general. Race setup must be correctly setup for usage every time any change is made or the location of the race is different
Take it from an old tire engineer: this post is so full of nonsense I can smell it from here.
There's a million other factors we could bring up but the bottom line is you should run the tire as the manufacture states. I would suggest you stay in 30psi-37 psi in general. Race setup must be correctly setup for usage every time any change is made or the location of the race is different
Take it from an old tire engineer: this post is so full of nonsense I can smell it from here.
#13
10-29-2008, 12:48 PM
[QUOTE=mahout;475836]
I'm with you.
And where's the moderator? Kill the thread already.
SO i have been seeing so many TPMS thread whats the recommended PSI.
There's a million other factors we could bring up but the bottom line is you should run the tire as the manufacture states. I would suggest you stay in 30psi-37 psi in general. Race setup must be correctly setup for usage every time any change is made or the location of the race is different
Take it from an old tire engineer: this post is so full of nonsense I can smell it from here.
There's a million other factors we could bring up but the bottom line is you should run the tire as the manufacture states. I would suggest you stay in 30psi-37 psi in general. Race setup must be correctly setup for usage every time any change is made or the location of the race is different
Take it from an old tire engineer: this post is so full of nonsense I can smell it from here.
And where's the moderator? Kill the thread already.
#14
10-29-2008, 02:06 PM
if your an engineer please feel free to add more facts.
i did stated that 30-37 psi is recommended. which should have been 33-34 on cold start sorry for a typo. but yea if you think that all my info is nonsense please prove me wrong, since you said your a tire engineer then why not put facts instead on commenting that all these are nonsence and please quote me on which are nonsense.
[quote=mahout;475836]
i did stated that 30-37 psi is recommended. which should have been 33-34 on cold start sorry for a typo. but yea if you think that all my info is nonsense please prove me wrong, since you said your a tire engineer then why not put facts instead on commenting that all these are nonsence and please quote me on which are nonsense.
[quote=mahout;475836]
SO i have been seeing so many TPMS thread whats the recommended PSI.
There's a million other factors we could bring up but the bottom line is you should run the tire as the manufacture states. I would suggest you stay in 30psi-37 psi in general. Race setup must be correctly setup for usage every time any change is made or the location of the race is different
Take it from an old tire engineer: this post is so full of nonsense I can smell it from here.
There's a million other factors we could bring up but the bottom line is you should run the tire as the manufacture states. I would suggest you stay in 30psi-37 psi in general. Race setup must be correctly setup for usage every time any change is made or the location of the race is different
Take it from an old tire engineer: this post is so full of nonsense I can smell it from here.
Last edited by jdmgpw04; 10-29-2008 at 02:38 PM.
#15
10-29-2008, 02:21 PM
There's already a STICKY thread on this topic in the ECO forum. How about we kill this one and let Mister Genius here go and read that one and respond.
https://www.fitfreak.net/forums/eco-...tires-mpg.html
Please read it, there's a complete discussion in there including plenty of pros and cons, and lots of facts that Mister Genius will need to contend with.
https://www.fitfreak.net/forums/eco-...tires-mpg.html
Please read it, there's a complete discussion in there including plenty of pros and cons, and lots of facts that Mister Genius will need to contend with.
#16
10-29-2008, 03:13 PM
yes i have thank you.
this thread is practically for those who are running anything 40PSI or over. i decided to put out this thread after reading some ridiculous PSI just to save GAS? oh come on now. one guy decided to put down 65PSI. do you think thats safe? i bet you you would probably say no. I know some other people are running 40PSI and again i am putting it out there that once the car is drivin in a certain amount of time, 40 PSI at cold start can up to 46-48 (depending on driving condition) my point basically its just not safe running higher PSI Manufacture PSI is recommended for best result. Do you think saving couple dollars and get better MPG (true). but do you think $91-120 saving a year is practically fawkin insane and if your (in general) so concerned about gas i can honestly tell you that you bought the fawkin wrong car. .............
i cant believe that most of you are disagreeing with what im saying. WOW
btw WDB if you read my entire thread i aswell put down the pros and cons. well not much of a pros but a lot of cons. ... .................................................. .....
this thread is practically for those who are running anything 40PSI or over. i decided to put out this thread after reading some ridiculous PSI just to save GAS? oh come on now. one guy decided to put down 65PSI. do you think thats safe? i bet you you would probably say no. I know some other people are running 40PSI and again i am putting it out there that once the car is drivin in a certain amount of time, 40 PSI at cold start can up to 46-48 (depending on driving condition) my point basically its just not safe running higher PSI Manufacture PSI is recommended for best result. Do you think saving couple dollars and get better MPG (true). but do you think $91-120 saving a year is practically fawkin insane and if your (in general) so concerned about gas i can honestly tell you that you bought the fawkin wrong car. .............
i cant believe that most of you are disagreeing with what im saying. WOW
btw WDB if you read my entire thread i aswell put down the pros and cons. well not much of a pros but a lot of cons. ... .................................................. .....
There's already a STICKY thread on this topic in the ECO forum. How about we kill this one and let Mister Genius here go and read that one and respond.
https://www.fitfreak.net/forums/eco-...tires-mpg.html
Please read it, there's a complete discussion in there including plenty of pros and cons, and lots of facts that Mister Genius will need to contend with.
https://www.fitfreak.net/forums/eco-...tires-mpg.html
Please read it, there's a complete discussion in there including plenty of pros and cons, and lots of facts that Mister Genius will need to contend with.
Last edited by jdmgpw04; 10-29-2008 at 03:24 PM.
#17
10-29-2008, 03:47 PM
jdmgpw04 I want to thank you posting your comments on this new thread even though there was one already out there. I think it’s a safety hazard more than anything. People want to inflate tire to the max, why not! Save few bucks here and there, even though you’ll pay for it in the back end. One problem though, most people don’t check their tire pressure before loading people in their cars, furniture, cement bags, firewood, who knows what else. I really think that if you already running the tires to the max, you overloading the tires, not necessarily the weigh might be an issue then but the pressure. It’s like lifting more than what you can before your back gives, keep lifting heavy objects to the max and see if your back doesn’t give out like your tires would. Now, running the tires at OEM PSI, what you looking at then is the max weigh the tires can handle. SO again, people don’t think about tire pressure before loading their vehicles. I think inflating my tires at OEM PSI works for me, that’s one less thing to worry about.
#18
10-29-2008, 10:03 PM
[quote=jdmgpw04;475922]if your an engineer please feel free to add more facts.
i did stated that 30-37 psi is recommended. which should have been 33-34 on cold start sorry for a typo. but yea if you think that all my info is nonsense please prove me wrong, since you said your a tire engineer then why not put facts instead on commenting that all these are nonsence and please quote me on which are nonsense.
Not all is nonsense but the whole is. Too much neat little rules.
The facts are car manufacturers specify tire pressures based on smooth ride. period.
Tire pressures are increased to 'stiffen' the carcass which yields more adhesion under lateral pressure. Hence 35 to 40 psi on track or canyon 'jaunts'. The harder you drive the more you need higher than recommended pressures.
NASCAR uses low pressures cold because of great heat buildup will get pressures - mostly the spring constants - up where adhesion is best. Or at least they expect it to be. And yes, increasing pressure does increase mpg because the tire gets rounder and harder.
Drag tires do run very low pressures because the carcass is made to fold and crease to increase contact surface.; street tires do not. If you tried to run a street tire like a drag tire all you would do is break traction and slow acceleration once moving because street tires don't 'strighten out' when rpm matches surface speed..
Stress cracks? where did you get that from? Millions of drivers have tire pressures 40 psi or more for thousands of miles. The correct pressure depends not only on the tire construction but also the wheel they are mounted on. The lower the profile and the wider the rim the greater pressure needed to 'flatten' the tread. Overinflation for one setup is underinflation for another. It ain't that simple.
As far as temperature rise is concerned my temperature gages say increases of 100 to 150F are not uncommon on the street and pressure increases of 10 to 20 psi not uncommon either. Most of my tires don't work very well unless the temp is 225 to 250F.
Every Mobil Economy run and the hybrid mpg contests I've seen up close ran 55 to 65 psi to reduce rolling resistance. Never saw one have a tire failure other than hitting a deep pothole or rock.
Non of those are unsafe conditions as a result of the carcass failure. Optimum tire pressures change to match the tire, the speed, and the road surface. Its not a neat little book of rules. Its far too complicated to say its this and so. The exceptions are legion.
i did stated that 30-37 psi is recommended. which should have been 33-34 on cold start sorry for a typo. but yea if you think that all my info is nonsense please prove me wrong, since you said your a tire engineer then why not put facts instead on commenting that all these are nonsence and please quote me on which are nonsense.
Not all is nonsense but the whole is. Too much neat little rules.
The facts are car manufacturers specify tire pressures based on smooth ride. period.
Tire pressures are increased to 'stiffen' the carcass which yields more adhesion under lateral pressure. Hence 35 to 40 psi on track or canyon 'jaunts'. The harder you drive the more you need higher than recommended pressures.
NASCAR uses low pressures cold because of great heat buildup will get pressures - mostly the spring constants - up where adhesion is best. Or at least they expect it to be. And yes, increasing pressure does increase mpg because the tire gets rounder and harder.
Drag tires do run very low pressures because the carcass is made to fold and crease to increase contact surface.; street tires do not. If you tried to run a street tire like a drag tire all you would do is break traction and slow acceleration once moving because street tires don't 'strighten out' when rpm matches surface speed..
Stress cracks? where did you get that from? Millions of drivers have tire pressures 40 psi or more for thousands of miles. The correct pressure depends not only on the tire construction but also the wheel they are mounted on. The lower the profile and the wider the rim the greater pressure needed to 'flatten' the tread. Overinflation for one setup is underinflation for another. It ain't that simple.
As far as temperature rise is concerned my temperature gages say increases of 100 to 150F are not uncommon on the street and pressure increases of 10 to 20 psi not uncommon either. Most of my tires don't work very well unless the temp is 225 to 250F.
Every Mobil Economy run and the hybrid mpg contests I've seen up close ran 55 to 65 psi to reduce rolling resistance. Never saw one have a tire failure other than hitting a deep pothole or rock.
Non of those are unsafe conditions as a result of the carcass failure. Optimum tire pressures change to match the tire, the speed, and the road surface. Its not a neat little book of rules. Its far too complicated to say its this and so. The exceptions are legion.
Last edited by mahout; 10-29-2008 at 10:19 PM.
#19
10-29-2008, 10:36 PM
[quote=mahout;476534]
DUDE YOU BETTER START EDITING YOUR POST. SOUNDS REALLY FREAKIN RIDICULOUS
SPECIALLY THIS ONE.
"Optimum tire pressures change to match the tire, the speed, and the road surface"
OMG
NEVER HEARD OF THAT BEFORE. I AM ACTUALLY LAUGHING MY ASS OFF RIGHT NOW. and you call yourself 40 year tire engineer.........................WOW.............. ...
OMG IM OUT PLEASE MOD CLOSE THIS DAMN THREAD..
if your an engineer please feel free to add more facts.
i did stated that 30-37 psi is recommended. which should have been 33-34 on cold start sorry for a typo. but yea if you think that all my info is nonsense please prove me wrong, since you said your a tire engineer then why not put facts instead on commenting that all these are nonsence and please quote me on which are nonsense.
Not all is nonsense but the whole is. Too much neat little rules.
The facts are car manufacturers specify tire pressures based on smooth ride. period.
Tire pressures are increased to 'stiffen' the carcass which yields more adhesion under lateral pressure. Hence 35 to 40 psi on track or canyon 'jaunts'. The harder you drive the more you need higher than recommended pressures.
NASCAR uses low pressures cold because of great heat buildup will get pressures - mostly the spring constants - up where adhesion is best. Or at least they expect it to be. And yes, increasing pressure does increase mpg because the tire gets rounder and harder.
Drag tires do run very low pressures because the carcass is made to fold and crease to increase contact surface.; street tires do not. If you tried to run a street tire like a drag tire all you would do is break traction and slow acceleration once moving because street tires don't 'strighten out' when rpm matches surface speed..
Stress cracks? where did you get that from? Millions of drivers have tire pressures 40 psi or more for thousands of miles. The correct pressure depends not only on the tire construction but also the wheel they are mounted on. The lower the profile and the wider the rim the greater pressure needed to 'flatten' the tread. Overinflation for one setup is underinflation for another. It ain't that simple.
As far as temperature rise is concerned my temperature gages say increases of 100 to 150F are not uncommon on the street and pressure increases of 10 to 20 psi not uncommon either. Most of my tires don't work very well unless the temp is 225 to 250F.
Every Mobil Economy run and the hybrid mpg contests I've seen up close ran 55 to 65 psi to reduce rolling resistance. Never saw one have a tire failure other than hitting a deep pothole or rock.
Non of those are unsafe conditions as a result of the carcass failure. Optimum tire pressures change to match the tire, the speed, and the road surface. Its not a neat little book of rules. Its far too complicated to say its this and so. The exceptions are legion.
i did stated that 30-37 psi is recommended. which should have been 33-34 on cold start sorry for a typo. but yea if you think that all my info is nonsense please prove me wrong, since you said your a tire engineer then why not put facts instead on commenting that all these are nonsence and please quote me on which are nonsense.
Not all is nonsense but the whole is. Too much neat little rules.
The facts are car manufacturers specify tire pressures based on smooth ride. period.
Tire pressures are increased to 'stiffen' the carcass which yields more adhesion under lateral pressure. Hence 35 to 40 psi on track or canyon 'jaunts'. The harder you drive the more you need higher than recommended pressures.
NASCAR uses low pressures cold because of great heat buildup will get pressures - mostly the spring constants - up where adhesion is best. Or at least they expect it to be. And yes, increasing pressure does increase mpg because the tire gets rounder and harder.
Drag tires do run very low pressures because the carcass is made to fold and crease to increase contact surface.; street tires do not. If you tried to run a street tire like a drag tire all you would do is break traction and slow acceleration once moving because street tires don't 'strighten out' when rpm matches surface speed..
Stress cracks? where did you get that from? Millions of drivers have tire pressures 40 psi or more for thousands of miles. The correct pressure depends not only on the tire construction but also the wheel they are mounted on. The lower the profile and the wider the rim the greater pressure needed to 'flatten' the tread. Overinflation for one setup is underinflation for another. It ain't that simple.
As far as temperature rise is concerned my temperature gages say increases of 100 to 150F are not uncommon on the street and pressure increases of 10 to 20 psi not uncommon either. Most of my tires don't work very well unless the temp is 225 to 250F.
Every Mobil Economy run and the hybrid mpg contests I've seen up close ran 55 to 65 psi to reduce rolling resistance. Never saw one have a tire failure other than hitting a deep pothole or rock.
Non of those are unsafe conditions as a result of the carcass failure. Optimum tire pressures change to match the tire, the speed, and the road surface. Its not a neat little book of rules. Its far too complicated to say its this and so. The exceptions are legion.
SPECIALLY THIS ONE.
"Optimum tire pressures change to match the tire, the speed, and the road surface"
OMG
NEVER HEARD OF THAT BEFORE. I AM ACTUALLY LAUGHING MY ASS OFF RIGHT NOW. and you call yourself 40 year tire engineer.........................WOW.............. ...
OMG IM OUT PLEASE MOD CLOSE THIS DAMN THREAD..
Last edited by jdmgpw04; 10-29-2008 at 10:48 PM.
#20
10-29-2008, 10:50 PM
While I think the OP makes a couple valid points, the biggest issue with over/under inflation is tire wear. It had been my habit to run 35 psi in about anything, and I did notice a major difference in center tread depth on my bride's VW (205/55 R16 Continental Contacts); I've reverted to the MFG's (30f/28r) pressure recommendations and am pleased with both ride and handling. It understeers far less; however, they also call for 32f/41r at max load, and 36f/44r for sustained speeds over 100 mph. Gotta love the Deutschers.
The point of this ramble is that it may be necessary to adjust tire pressure depending on circumstance, and that the MFG's suggestions are a great place to start. While they may hedge on the side of good ride, the numbers aren't likely to be too far off.
Also, IMHO, outright tire failure is unlikely unless the air pressure is grossly over or under what's suggested.
Moon
The point of this ramble is that it may be necessary to adjust tire pressure depending on circumstance, and that the MFG's suggestions are a great place to start. While they may hedge on the side of good ride, the numbers aren't likely to be too far off.
Also, IMHO, outright tire failure is unlikely unless the air pressure is grossly over or under what's suggested.
Moon