Tire Pressure: How Low Can You Go?
#3
02-12-2011, 03:45 AM
Are you running stock suspension? With stock pressures its not that bad. Try some nitrogen... that will help a bit plus controls the inside temps better than just air. Give it a go. Many tire shops have it nowadays.
#4
02-12-2011, 06:56 AM
Nitrogen would help.
Have you considered dropping down a wheel size and getting a thicker tire? Seems like your roads would warrant that type of peice of mind...
Have you considered dropping down a wheel size and getting a thicker tire? Seems like your roads would warrant that type of peice of mind...
#5
02-12-2011, 07:09 AM
I think those tire pressures are fine, but I am wondering about the rear rattle maybe a rear quarter window issue. I remember there being some problems with something loose in that area? A spot weld of something?
#6
02-12-2011, 09:19 AM
I got my car back from a service today and I noticed they brought the tire pressure up to the psi spec'd on the door. The drive home was much more rough than ever before and the car now rattles quite a bit. It seems like the most common rattle is coming from somewhere near the passenger side rear interior panel. I'm sure I can find it but I'm more concerned with the dramatic increase in harshness. The guy I bought my car from (just last month) said the local dealer told him it was ok to ride on lower tire pressures. That same dealer did the PPI on the car for me and apparently they were ok with 29 in the front and 35 in the rear (when cold).
I've gotten used to driving the car at those pressures. Now that the car has the tire pressures brought up to spec, it's just too freagin' rough on these lousy MD highways.
So a question.. how low can the pressure be and still be safe?
I've gotten used to driving the car at those pressures. Now that the car has the tire pressures brought up to spec, it's just too freagin' rough on these lousy MD highways.
So a question.. how low can the pressure be and still be safe?
2. 29 front, 36 rear = as mentioned by Ruf_Turbo, this is (roughly) the correct numbers to use for cold tire pressures.
3. Best way to set pressure, IMHO: Your car should come with TPMS standard. Read the manual and set the car to partial load, summer tire.
Then, use the differential reading (should be in the manual), set the car to +0 at all 4 wheels. This should come out to 29-30 front and 35-36 rear more or less and is your baseline. You could vary a little bit around this depending on suspension setup and personal preference. (Using cup tires means you'll have to vary a lot more, like minus 3 or 4 -- but that has nothing to do with your case here.)
4. Overinflated tire (within reasons) improves steering feel, but way too high then ride becomes too rough and traction and cornering stability becomes an issue -- tirerack has a good discussion on this IIRC. Certainly using the door panel numbers bring you to this unsafe area IMHO. For whatever reasons, my car always, always comes back from dealers overinflated
, probably because the guys just read the door panel specs without reading the warning note right next to it.5. OTOH, underinflated tire deforms with cornering (not good) and decreases steering feel. But using the TPMS as mentioned above, you are not in this range, meaning, you are not underflating at 29/36 cold.
Good luck and hope this helps.
Last edited by cannga; 02-12-2011 at 12:18 PM.
#7
02-12-2011, 10:38 AM
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Never could understand this as "air" is 78% Nitrogen anyways.
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#8
02-12-2011, 03:13 PM
Nitrogen has no effect on temperature stability, ride comfort, or saving the whales.
Benefits:
It is relatively "dry", meaning you will have a TINY bit less water vapor in your tires. Commercial nitrogen is only about 95% pure, so you really only step up to 95% from 78%.
Nitrogen molecules are also slightly larger than oxygen molecules and leak through the tire more slowly, so you will lose 2.5 lbs less air pressure per Year.
Just so you know, all gases expand at the same rate except for that tiny amount of water vapor. It's called Avogadro's Law. Pure science. no marketing BS.
Without question, this whole Nitrogen thing is a pet peeve of mine. It is brilliantly marketed to the uninformed. Some shops charge $80 or more for a fill, claiming every benefit known to mankind.
Nitrogen is just an inert gas. Invest half that $80 in a good tire gauge, and spend the rest on a nice bottle of Chardonnay.
Or choose helium instead and your car will be lighter (just kidding).
Benefits:
It is relatively "dry", meaning you will have a TINY bit less water vapor in your tires. Commercial nitrogen is only about 95% pure, so you really only step up to 95% from 78%.
Nitrogen molecules are also slightly larger than oxygen molecules and leak through the tire more slowly, so you will lose 2.5 lbs less air pressure per Year.
Just so you know, all gases expand at the same rate except for that tiny amount of water vapor. It's called Avogadro's Law. Pure science. no marketing BS.
Without question, this whole Nitrogen thing is a pet peeve of mine. It is brilliantly marketed to the uninformed. Some shops charge $80 or more for a fill, claiming every benefit known to mankind.
Nitrogen is just an inert gas. Invest half that $80 in a good tire gauge, and spend the rest on a nice bottle of Chardonnay.
Or choose helium instead and your car will be lighter (just kidding).
#10
02-12-2011, 05:54 PM
Me neither.....just going by advice of my tire shop. The guy who is owns it is an ex racer so gave me that advice. I assumed he knew what he was talking about. Ive used nitrogen myself in past P's and found it (seemed) to dampen things a wee bit. I used it on my 997s with damptronics in hope of softening it a bit. Maybe its the placebo effect....it could be...as i was looking for anything at that stage to soften the ride. I haven't bothered with it much after the first fill as when you bleed off pressure at the track unless you've got more of it to refill later on then you end up contaminating it with regular air.
Interesting. I'll ask my tire guy again when i talk to him next.....and put it to him he's been BSing me 
. Altho he's never charged me for it so far so i wont go in too hard.
. Ah well...im sure that darn placebo effect has had its way with most of us at one stage in the game.. 
.
Nitrogen has no effect on temperature stability, ride comfort, or saving the whales.
Benefits:
It is relatively "dry", meaning you will have a TINY bit less water vapor in your tires. Commercial nitrogen is only about 95% pure, so you really only step up to 95% from 78%.
Nitrogen molecules are also slightly larger than oxygen molecules and leak through the tire more slowly, so you will lose 2.5 lbs less air pressure per Year.
Just so you know, all gases expand at the same rate except for that tiny amount of water vapor. It's called Avogadro's Law. Pure science. no marketing BS.
Benefits:
It is relatively "dry", meaning you will have a TINY bit less water vapor in your tires. Commercial nitrogen is only about 95% pure, so you really only step up to 95% from 78%.
Nitrogen molecules are also slightly larger than oxygen molecules and leak through the tire more slowly, so you will lose 2.5 lbs less air pressure per Year.
Just so you know, all gases expand at the same rate except for that tiny amount of water vapor. It's called Avogadro's Law. Pure science. no marketing BS.
. Altho he's never charged me for it so far so i wont go in too hard.. Ah well...im sure that darn placebo effect has had its way with most of us at one stage in the game.. .
Last edited by speed21; 02-12-2011 at 05:59 PM.
#11
02-12-2011, 09:35 PM
Registered User
Join Date: May 2007
Location: Pittsburgh Area
Age: 73
Posts: 1,946
Rep Power: 169 Nitrogen has no effect on temperature stability, ride comfort, or saving the whales.
Benefits:
It is relatively "dry", meaning you will have a TINY bit less water vapor in your tires. Commercial nitrogen is only about 95% pure, so you really only step up to 95% from 78%.
Nitrogen molecules are also slightly larger than oxygen molecules and leak through the tire more slowly, so you will lose 2.5 lbs less air pressure per Year.
Just so you know, all gases expand at the same rate except for that tiny amount of water vapor. It's called Avogadro's Law. Pure science. no marketing BS.
Without question, this whole Nitrogen thing is a pet peeve of mine. It is brilliantly marketed to the uninformed. Some shops charge $80 or more for a fill, claiming every benefit known to mankind.
Nitrogen is just an inert gas. Invest half that $80 in a good tire gauge, and spend the rest on a nice bottle of Chardonnay.
Or choose helium instead and your car will be lighter (just kidding).
Benefits:
It is relatively "dry", meaning you will have a TINY bit less water vapor in your tires. Commercial nitrogen is only about 95% pure, so you really only step up to 95% from 78%.
Nitrogen molecules are also slightly larger than oxygen molecules and leak through the tire more slowly, so you will lose 2.5 lbs less air pressure per Year.
Just so you know, all gases expand at the same rate except for that tiny amount of water vapor. It's called Avogadro's Law. Pure science. no marketing BS.
Without question, this whole Nitrogen thing is a pet peeve of mine. It is brilliantly marketed to the uninformed. Some shops charge $80 or more for a fill, claiming every benefit known to mankind.
Nitrogen is just an inert gas. Invest half that $80 in a good tire gauge, and spend the rest on a nice bottle of Chardonnay.
Or choose helium instead and your car will be lighter (just kidding).
#12
02-12-2011, 11:03 PM
Mike,
No disrespect intended.
Air, especially in tires, CAN contain more than a 'TINY' bit of water vapor. Water vapor does cause expansion and contraction with temperature variations. Using a nitrogen purging system removes most (99%+) of the water vapor.
Avogardo's Law states that gases at the same volume, pressure, and temperature will have the same amount of molecules not that they expand at the same rate. If that were the case everything would boil and freeze at the same rate...and that doesn't happen.
I wouldn't use nitrogen either if it was $20 a tire every time but I paid $5 a tire once and my dealer does it free after that so it's worth it to me. And it's for the life of the vehicle, not the tire.
Plus I have found my track tires deviate a lot less when they are filled with nitrogen.
No disrespect intended.
Nitrogen has no effect on temperature stability, ride comfort, or saving the whales.
Benefits:
It is relatively "dry", meaning you will have a TINY bit less water vapor in your tires. Commercial nitrogen is only about 95% pure, so you really only step up to 95% from 78%.
Benefits:
It is relatively "dry", meaning you will have a TINY bit less water vapor in your tires. Commercial nitrogen is only about 95% pure, so you really only step up to 95% from 78%.
Without question, this whole Nitrogen thing is a pet peeve of mine. It is brilliantly marketed to the uninformed. Some shops charge $80 or more for a fill, claiming every benefit known to mankind.
Nitrogen is just an inert gas. Invest half that $80 in a good tire gauge, and spend the rest on a nice bottle of Chardonnay.
Nitrogen is just an inert gas. Invest half that $80 in a good tire gauge, and spend the rest on a nice bottle of Chardonnay.
Plus I have found my track tires deviate a lot less when they are filled with nitrogen.
#13
02-12-2011, 11:37 PM
Avogardo's Law states that gases at the same volume, pressure, and temperature will have the same amount of molecules not that they expand at the same rate. If that were the case everything would boil and freeze at the same rate...and that doesn't happen. Plus I have found my track tires deviate a lot less when they are filled with nitrogen.
.
#14
02-13-2011, 05:09 AM
No disrespect taken.
Tires DO NOT deviate less when filled with Nitrogen. There is no science to support this claim.
However, the placebo effect of Nitrogen is well documented in these forums.
Science:
No matter what gas you fill your tires with they will expand at the same rate when heated. The exception is the partial pressure of what small amount of water vapor is actually present in the tire. This is usually a TINY amount.
I am well aware that race teams use Nitrogen in an attempt to remove even this tiny variable.
I stand by my first post. And all the previous ones that I have made on this subject. Nitrogen for automobile tires is extremely well marketed but of little value.
Tires DO NOT deviate less when filled with Nitrogen. There is no science to support this claim.
However, the placebo effect of Nitrogen is well documented in these forums.
Science:
No matter what gas you fill your tires with they will expand at the same rate when heated. The exception is the partial pressure of what small amount of water vapor is actually present in the tire. This is usually a TINY amount.
I am well aware that race teams use Nitrogen in an attempt to remove even this tiny variable.
I stand by my first post. And all the previous ones that I have made on this subject. Nitrogen for automobile tires is extremely well marketed but of little value.
Mike,
No disrespect intended.
Air, especially in tires, CAN contain more than a 'TINY' bit of water vapor. Water vapor does cause expansion and contraction with temperature variations. Using a nitrogen purging system removes most (99%+) of the water vapor.
Avogardo's Law states that gases at the same volume, pressure, and temperature will have the same amount of molecules not that they expand at the same rate. If that were the case everything would boil and freeze at the same rate...and that doesn't happen.
I wouldn't use nitrogen either if it was $20 a tire every time but I paid $5 a tire once and my dealer does it free after that so it's worth it to me. And it's for the life of the vehicle, not the tire.
Plus I have found my track tires deviate a lot less when they are filled with nitrogen.
No disrespect intended.
Air, especially in tires, CAN contain more than a 'TINY' bit of water vapor. Water vapor does cause expansion and contraction with temperature variations. Using a nitrogen purging system removes most (99%+) of the water vapor.
Avogardo's Law states that gases at the same volume, pressure, and temperature will have the same amount of molecules not that they expand at the same rate. If that were the case everything would boil and freeze at the same rate...and that doesn't happen.
I wouldn't use nitrogen either if it was $20 a tire every time but I paid $5 a tire once and my dealer does it free after that so it's worth it to me. And it's for the life of the vehicle, not the tire.
Plus I have found my track tires deviate a lot less when they are filled with nitrogen.
#15
02-13-2011, 07:46 AM
That was your imagination. You are not going to feel any difference in the ride. Pressure is pressure no matter what gas supplies it.