for my first post lets talk tire pressures
- Thread starter KST
- Start date
- Status
I found in my Honda Accord that recommended pressures resulted in my Michelin's showing wear beyond the limiter marks as did others from cornering and weight in the trunk.
So I went from 32 psi to 35 psi and I am good to go.
Max pressure is 40 psi.
As with most things in life a recommendation is a recommendation and my needs were not met with was recommended.
So I made a wise educated change. It will make for safer and longer tire life.
So I went from 32 psi to 35 psi and I am good to go.
Max pressure is 40 psi.
As with most things in life a recommendation is a recommendation and my needs were not met with was recommended.
So I made a wise educated change. It will make for safer and longer tire life.
Manufacturers tire pressures are usually for the best/soft ride, I have most my car pressures 4-6 PSI above recommended for every day driving and found that the ride is firm but not hash, the steering is quicker and tire wear evenly and better fuel economy. But the Honda S2000 performs best with rear tires at recommended and front tires at 2 PSI above. For long trips I upped all tires to about 8-10 PSI above recommended to reduce the heat built-up at triple-digit speed.
You should try an increment of 2 PSI for each week until you think the ride is too hash then reduce it down to where you find a good compromise in handling/performance and ride.
You should try an increment of 2 PSI for each week until you think the ride is too hash then reduce it down to where you find a good compromise in handling/performance and ride.
There's a theory that when you go too high, the tires don't flex and the shocks turn the little bumps into heat energy. (and adds wear to your ball joints and unsprung gizmos.)
However if the tire could flex more, it would push back against that bump, propelling you forward.
Do I buy it? IDK. I run a few pounds over the door jamb, observing the 4 psi bias towards the front, and like how the sidewalls hold up when cornering.
However if the tire could flex more, it would push back against that bump, propelling you forward.
Do I buy it? IDK. I run a few pounds over the door jamb, observing the 4 psi bias towards the front, and like how the sidewalls hold up when cornering.
How would you know which way to bias the pressures without knowing what kind of car?
Typically I would agree with the 4 pounds over spec. But there are too many variables to just lay a blanket recommendation on you.
How about some info on the car? Tires, stock or larger? Driving style? Etc.
Typically I would agree with the 4 pounds over spec. But there are too many variables to just lay a blanket recommendation on you.
How about some info on the car? Tires, stock or larger? Driving style? Etc.
Normally, the higher profile ratio (70 or 80) tires show reliable correlation between the fuel efficiency and the pressure. The higher the better. This is not the case with the lower profile tires though. Especially with modern/expensive ones. You still may want to increase the pressure for improving handling or whatever you goal is but don't expect to save a lot of gas. FYI: the recommended pressure on the sticker is already a little higher (usually 10-15%) than your tires actually need for the given load. If you are interested to do some math you can estimate the minimum pressure for the front and the rear tires for you vehicle at different load conditions. All the info regarding tires can be found in the "ETRTO Standards Manual". Just google it.
Originally Posted By: Prelude
.........FYI: the recommended pressure on the sticker is already a little higher (usually 10-15%) than your tires actually need for the given load.......
Just so this is not mis-understood, the additional load carrying capacity - commonly called reserve capacity - is an outgrowth of the Ford/Firestone situation a few years back. Remember the arguement about inflation pressure? That was about reserve capacity - and Ford didn't have any. In fact, many vehicles didn't have any!
Given the situation at the time, it was agreed - and it makes good engineering sense - to over-specify the pressure (and hence, the load carrying capacity) It was also discovered that the way the load carrying capacity was specified was not adequate for certain driving conditions. Since it is impossible to revise the load table (as published by ETRTO, or the Tire and Rim Association), the tire manufacturers advised the vehicle manufacturers to make appropriate changes in their tire size / pressure recommendations.
So while the load carrying capacity seems to be over-specified, in reality it is just making up for a built-in inadequancy. I would advise against taking the ETRTO and TRA load tables literally.
.........FYI: the recommended pressure on the sticker is already a little higher (usually 10-15%) than your tires actually need for the given load.......
Just so this is not mis-understood, the additional load carrying capacity - commonly called reserve capacity - is an outgrowth of the Ford/Firestone situation a few years back. Remember the arguement about inflation pressure? That was about reserve capacity - and Ford didn't have any. In fact, many vehicles didn't have any!
Given the situation at the time, it was agreed - and it makes good engineering sense - to over-specify the pressure (and hence, the load carrying capacity) It was also discovered that the way the load carrying capacity was specified was not adequate for certain driving conditions. Since it is impossible to revise the load table (as published by ETRTO, or the Tire and Rim Association), the tire manufacturers advised the vehicle manufacturers to make appropriate changes in their tire size / pressure recommendations.
So while the load carrying capacity seems to be over-specified, in reality it is just making up for a built-in inadequancy. I would advise against taking the ETRTO and TRA load tables literally.
The standard specifies the lowest acceptable COLD tire pressure for speeds up to 160 km/h. Since people don't check the pressure every day and some of them do it at a gas station when the tires are not cold, it is a good idea to give some safety margin by recommending a higher pressure. No doubt about that.
Originally Posted By: Prelude
The standard specifies the lowest acceptable COLD tire pressure for speeds up to 160 km/h. Since people don't check the pressure every day and some of them do it at a gas station when the tires are not cold, it is a good idea to give some safety margin by recommending a higher pressure. No doubt about that.
Just so we are absolutely clear on this:
Do NOT take the ETRTO (or JATMA or TRA) load tables at face value. Do NOT assume you can run a tire at the loads specified for the inflation pressure without negative consequences.
The standard specifies the lowest acceptable COLD tire pressure for speeds up to 160 km/h. Since people don't check the pressure every day and some of them do it at a gas station when the tires are not cold, it is a good idea to give some safety margin by recommending a higher pressure. No doubt about that.
Just so we are absolutely clear on this:
Do NOT take the ETRTO (or JATMA or TRA) load tables at face value. Do NOT assume you can run a tire at the loads specified for the inflation pressure without negative consequences.
Does it mean that the designers use something else rather than an approved official document which every tire manufacture refers to on their web sites? Why are my calculated figures for a few randomly chosen cars (fully loaded) very close to the actual recommended pressure for these cars? I don't believe it is a coincidence. You can easily prove me wrong by giving an example showing that the recommended pressure and the pressure obtained from the tables do not match by a wide margin. I am really interested to see that.
First, you said this:
Originally Posted By: Prelude
........FYI: the recommended pressure on the sticker is already a little higher (usually 10-15%) than your tires actually need for the given load.......
Then you said this:
Originally Posted By: Prelude
........Why are my calculated figures for a few randomly chosen cars (fully loaded) very close to the actual recommended pressure for these cars?.....
So which is it? 10-15% or very close?
Originally Posted By: Prelude
........ You can easily prove me wrong by giving an example showing that the recommended pressure and the pressure obtained from the tables do not match by a wide margin. I am really interested to see that.
Fair enough, but just so we are clear - "wide margin" means 10=15% or more, right?
You'll have to give me a little time to dig this stuff up. I'm starting from scratch.
And just to be fair, since you've already calculated a few, why don't you post your calculations as well. BTW, it might be helpful if you posted a reference where you got your data.
Originally Posted By: Prelude
........FYI: the recommended pressure on the sticker is already a little higher (usually 10-15%) than your tires actually need for the given load.......
Then you said this:
Originally Posted By: Prelude
........Why are my calculated figures for a few randomly chosen cars (fully loaded) very close to the actual recommended pressure for these cars?.....
So which is it? 10-15% or very close?
Originally Posted By: Prelude
........ You can easily prove me wrong by giving an example showing that the recommended pressure and the pressure obtained from the tables do not match by a wide margin. I am really interested to see that.
Fair enough, but just so we are clear - "wide margin" means 10=15% or more, right?
You'll have to give me a little time to dig this stuff up. I'm starting from scratch.
And just to be fair, since you've already calculated a few, why don't you post your calculations as well. BTW, it might be helpful if you posted a reference where you got your data.
First installment: 2010 Ford Taurus SEL. Here’s the vehicle tire placard:
http://www.barrystiretech.com/2010taurusplacardsmall.jpg
Front GAWR = 2820#
Rear GAWR = 2520#
P255/45R19 @ 32 psi Front and Rear
Here’s a copy of the load table. This one is from Tire Guides (courtesy of The Tire and Rim Association):
http://www.barrystiretech.com/abbtratireguides.jpg
P255/45R19 @ 32 psi = 1667#
Note: Unfortunately, it isn’t clear that the tire in question is the 100 Load Index (Standard Load), not the 94 Load Index (Light Load)
So for both the front and the rear the load carrying capacity of the tires is 3334#. That means the front tires are at 85% and the rears are at 76% of the load carrying capacity of the tires.
http://www.barrystiretech.com/2010taurusplacardsmall.jpg
Front GAWR = 2820#
Rear GAWR = 2520#
P255/45R19 @ 32 psi Front and Rear
Here’s a copy of the load table. This one is from Tire Guides (courtesy of The Tire and Rim Association):
http://www.barrystiretech.com/abbtratireguides.jpg
P255/45R19 @ 32 psi = 1667#
Note: Unfortunately, it isn’t clear that the tire in question is the 100 Load Index (Standard Load), not the 94 Load Index (Light Load)
So for both the front and the rear the load carrying capacity of the tires is 3334#. That means the front tires are at 85% and the rears are at 76% of the load carrying capacity of the tires.
- Status
