30 vs 35 PSI - Tire Pressure

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cheez

Golden Member
Nov 19, 2010
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OP is rocking a buick. If the sidewall is any less than a 70 I'd be suprised. 40+ PSI is silly. Advice is best when it comes from a solid base of knowledge ........http://forums.anandtech.com/showthread.php?t=2343409 :whiste:
What's loose steering and shocks replacement got to do with OP's question about PSI's for tires? Just cause I asked a few questions doesn't mean I know nothing, you forum troll..... You want water bed ride go ahead and stick with your 30 PSI. There's no right / wrong answer to the PSI's as it varies for the user. The car will respond to drivers input more slowly. This will actually make it more dangerous. Greater chance of getting an accident.


cheez
 
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monkeydelmagico

Diamond Member
Nov 16, 2011
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What's loose steering and shocks replacement got to do with OP's question about PSI's for tires? Just cause I asked a few questions doesn't mean I know nothing, you forum troll..... You want water bed ride go ahead and stick with your 30 PSI. There's no right / wrong answer to the PSI's as it varies for the user. The car will respond to drivers input more slowly. This will actually make it more dangerous. Greater chance of getting an accident.


cheez
Overinflation runs just as much risk as underinflation. Contact patch. Yes, there are right and wrong answers. Your experience bending rims and not knowing how to even diagnose much less fix your own car makes some of your "suggestions" seem a bit difficult to validate. I understand you are working from your own experience. If you read some of the other poster's suggestions you may realize yours are not good ones.

I'd rather be a troll than an idiot.
 

cheez

Golden Member
Nov 19, 2010
1,722
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Overinflation runs just as much risk as underinflation. Contact patch.
As long as it's within tire manufacturer's spec for the PSI the tires will be fine. You like the water bed ride, stick with your 30 PSI. I said this already.

Yes, there are right and wrong answers.
There are NO right and wrong answers, but if you go too far that's when you get problems... i.e. wheel damage because you went over a pot hole with 28 PSI.

Your experience bending rims and not knowing how to even diagnose much less fix your own car makes some of your "suggestions" seem a bit difficult to validate.
The rims were inspected by the technician after I went over the pot hole. The edge of the rim was bent due to the pot hole I ran over. That is simply what I am telling you. It doesn't require a rocket scientist or someone with extreme knowledge of cars to say this. You do not get to dictate who has the right to speak and who does not due to their level of expertise or experience.

I understand you are working from your own experience. If you read some of the other poster's suggestions you may realize yours are not good ones.

I'd rather be a troll than an idiot.
This tells me you may have hard time dealing with people in the real world. You wouldn't say anything like this in person face to face, but it is easy to say such things over the internet. Just like hiding behind that couch of yours. Nice.



cheez
 
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pauldun170

Diamond Member
Sep 26, 2011
8,852
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For a 2005 Buick Century, Buick's recommendation of 30 is perfectly fine and normal for the tire size and class of car. 30psi-35psi is a very common recommendation.
Do not go by the sidewall on the tire.

As much as I like the "Ignore the manufacturer....I always do XXXX so if I do it you 'll be fine too!!!" posts, stick with what the engineering staff at the manfufacturer recommend. If there is an issue with handling, I would suspect the culprit is that its an 8 year car on 8 year old suspension.
 
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pauldun170

Diamond Member
Sep 26, 2011
8,852
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Would upping it to 35 PSI help with Gas Mileage, which is my main focus?
Not really. A negligible amount if all you are doing is highway.
If you want to maximize gas mileage, use a light foot and be smooth with your driving. Spend the least amount of time on the brake as you can.

Highway miles are pretty decent in that car and if you don't drive like an ass you should be able to hit 25mpg mixed driving.
 

Eureka

Diamond Member
Sep 6, 2005
3,822
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The proper PSI depends on the car. Overinflation does affect handling adversely as well. Miata auto-xers tend to be religious about their PSI.

As a general rule of thumb, a bit higher tends to be better for fuel economy, but too high causes over-inflation issues such as mid-tread tire wear.

I would just keep it to near the door jamb recommendation, maybe a couple of pounds higher. 35 over 30 is a 17% increase in pressure... pretty significant.
 

jacktesterson

Diamond Member
Sep 28, 2001
5,493
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For a 2005 Buick Century, Buick's recommendation of 30 is perfectly fine and normal for the tire size and class of car. 30psi-35psi is a very common recommendation.
Do not go by the sidewall on the tire.

As much as I like the "Ignore the manufacturer....I always do XXXX so if I do it you 'll be fine too!!!" posts, stick with what the engineering staff at the manfufacturer recommend. If there is an issue with handling, I would suspect the culprit is that its an 8 year car on 8 year old suspension.

No issues. Just wondering.

Suspension was fully replaced last year. Car is one owner vehicle. I've kept it the best I can.

Anyways, I'll stick to the specs on the door and continue to check the air once a month
 

jacktesterson

Diamond Member
Sep 28, 2001
5,493
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Not really. A negligible amount if all you are doing is highway.
If you want to maximize gas mileage, use a light foot and be smooth with your driving. Spend the least amount of time on the brake as you can.

Highway miles are pretty decent in that car and if you don't drive like an ass you should be able to hit 25mpg mixed driving.
Agreed. I average 25 or so mixed, 34 on highway
 

Pariah

Elite Member
Apr 16, 2000
7,357
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My car actually gives different recommendations based on how fat the people in the car are.

If "occupant and cargo weight 470 pounds or less" put in 30 psi. If "occupant and cargo weighs up to 740 pounds" put in 35 psi.

With a useless trunk and back seats that no fat person would ever be able to get to, I have no idea how you would ever be able to reach 740lbs, but I inflate to 35 psi anyway. The car feels sharper in corners and like it rolls better with the higher psi.
 

jacktesterson

Diamond Member
Sep 28, 2001
5,493
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That's great.
You're doing better than my 4 banger Camry.
I also own a 2004 Pontiac Montana with a 3.4L Engine, It has about 160,000 Miles on it.

The Century has a 3.1L engine that is my understanding almost identical to the 3.4L engine other than smaller displacement.

Not sure if the Van is heavier, but its awful on gas compared to the Century. The van is a Short one with 6 captains chairs. I only average about 19 MPG mixed and 26-27 on the highway.

The van is also in great condition for the Year and Amount of miles.

Nothing special for vehicles, but keeps me proud for some reason to keep them solid.

Off topic I know.
 
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TridenT

Lifer
Sep 4, 2006
16,810
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Here's my experience from running about 37-40PSI on all four tires in my civic:

Gas mileage, sometimes it goes up. It's hard to say. I've achieved higher maximum gas mileage on higher PSI values than ever before. However, I achieved basically the same gas mileage until about 6-9 months ago when I suddenly went up dramatically (Not sure what happened, to be honest). I ran at the 29-30 PSI recommendation in the car before and could never hit 35mpg on any tank. Running 37-40PSI, I've hit about 38MPG on maybe a few tanks. But, I've been running 37-40PSI for probably about 2 years now. Never hit 35MPG+ until about a year ago. So, I would say, gas mileage wise... YMMV. (derpa-pun-herp)

Traction wise... To me, it seemed like a very noticeable difference! (Maybe it's all in my head though?) It felt like I could immediately tell the difference. It was easier to burn out, far less grip in the corners, and by far way less grip IN THE RAIN. If you're concerned at all about tire grip, go with the recommended PSI. You're kind of trading your life for maybe a couple extra MPG. I don't know if that's worth it. I'm highly considering going back to 29-30PSI just to see if I can get the same MPG numbers on that inflation.

Also, OP, you might want to consider tire wear. It might wear out the tires faster from what I understand. Something to consider if you have expensive tires and it wears them out prematurely.
 

Gillbot

Lifer
Jan 11, 2001
28,830
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Here's my experience from running about 37-40PSI on all four tires in my civic:

Gas mileage, sometimes it goes up. It's hard to say. I've achieved higher maximum gas mileage on higher PSI values than ever before. However, I achieved basically the same gas mileage until about 6-9 months ago when I suddenly went up dramatically (Not sure what happened, to be honest). I ran at the 29-30 PSI recommendation in the car before and could never hit 35mpg on any tank. Running 37-40PSI, I've hit about 38MPG on maybe a few tanks. But, I've been running 37-40PSI for probably about 2 years now. Never hit 35MPG+ until about a year ago. So, I would say, gas mileage wise... YMMV. (derpa-pun-herp)

Traction wise... To me, it seemed like a very noticeable difference! (Maybe it's all in my head though?) It felt like I could immediately tell the difference. It was easier to burn out, far less grip in the corners, and by far way less grip IN THE RAIN. If you're concerned at all about tire grip, go with the recommended PSI. You're kind of trading your life for maybe a couple extra MPG. I don't know if that's worth it. I'm highly considering going back to 29-30PSI just to see if I can get the same MPG numbers on that inflation.

Also, OP, you might want to consider tire wear. It might wear out the tires faster from what I understand. Something to consider if you have expensive tires and it wears them out prematurely
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May 13, 2009
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I'd go with manufacturer recommendations. It's a grandpa car. What makes it great is boat like handling and the plushness of the ride.
 

Gillbot

Lifer
Jan 11, 2001
28,830
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I'd love to see sources showing that inflating your tires well above recommended PSI is going to lower tire wear.
It increases wear.
http://www.hankooktireusa.com/Serv/Inflation.aspx?pageNum=3&subNum=3&ChildNum=4

Overinflation

Higher inflated tires cannot isolate road irregularities well and this leads to a harsher ride.
Tires can also be damaged more easily, lowering safety levels.

Safety - More susceptible to damage from external factors (potholes, debris)
Economy - Speeds up wear, in particular wear of central tread part
 

phucheneh

Diamond Member
Jun 30, 2012
7,306
4
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Sure.....

I thought it was pretty much common sense that over-inflation decreases contact patch and thus reduces traction.
Traction and handling capabilities aren't always the same, though. Your average FWD just seems more responsive with a little extra pressure.

Which is the general idea on just about any car. More pressure is more immediate response, less pressure is more overall traction/grip. Too far in either direction feels like crap...but 25% above spec seems to feel a lot better than 25% below. That would be running a car with 32psi spec at 40 vs 24. I doubt most people would notice the former; I'm generally afraid of those who wouldn't notice the latter.

I don't see the wear thing, though. How do people argue that you're both decreasing friction and increasing wear? Center wear, yeah; overall life of the time...I don't buy it. And like I already said- I always err on the side of the center wearing out first, rather than the edges.

edit: and I'm not arguing for 'inflate to sidewall,' BTW. More that I simply go a little higher than spec because I know the tires won't be checked. If you check them every week, sure, go with the jamb's spec. For your average person that only gets them checked at their quarterly oil change, I say keep them on the high side when actually DO get checked.

Keep in mind that lube guys were already lazy (or just overly-pressured to churn cars out quickly). Now they also have TPMS as an excuse to say 'why bother checking the tires?'
 
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railer

Golden Member
Apr 15, 2000
1,545
59
91
For a 2005 Buick Century, Buick's recommendation of 30 is perfectly fine and normal for the tire size and class of car. 30psi-35psi is a very common recommendation.
Do not go by the sidewall on the tire.

As much as I like the "Ignore the manufacturer....I always do XXXX so if I do it you 'll be fine too!!!" posts, stick with what the engineering staff at the manfufacturer recommend. If there is an issue with handling, I would suspect the culprit is that its an 8 year car on 8 year old suspension.
^ this guy.

Heck, the tolerance on any cheap tire pressure gauge is probably +/- 2 or 3 psi anyway. I'm sure you'll notice very little difference at 35 psi from a ride/handling standpoint, and no difference at all from an mpg standpoint. But as others have stated your tires will of course lose pressure over time, so it's probably just as easy to go +15% on the initial pressure, rather then check the pressure 3x/week.
 

TridenT

Lifer
Sep 4, 2006
16,810
45
91
Sure.....

I thought it was pretty much common sense that over-inflation decreases contact patch and thus reduces traction.
Yes, it could. I was just putting in there that maybe it's all in my head though because I don't really know; I cannot easily measure the difference between the contact patches.
 

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