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45PSI Tires MPG vs. 34PSI Tires MPG

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  #261  
Old 03-05-2018, 12:15 PM
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Originally Posted by fitchet
I inflate my tires to the recommendation in the drivers door, which is the MANUFACTURER of the vehicles recommendation...FOR the vehicle. NOT the MAX the tire manufacturer sets for the tire itself.

To me the tire recommendation is like a extension ladder. The MAX for the tire is like a extension ladder that has a sticker that says it can be extended to a MAX of 20 ft.

If you only need to go 12 ft high, do you extend the ladder to 20 ft? No. Because it's not needed or even safe for the situation. You don't do it just because the ladder say's it can do it.

I feel the same about Tire Inflation. The manufacturer of the vehicle, familiar with the design of the vehicle offers a recommendation FOR the vehicle. That' the PSI I go with.

The Tire sidewall...is just like the sticker on the extension ladder. It's the MAX the tire manufacturer says the tire can be inflated. But it's NOT a recommendation for vehicle you are driving.
Your driving style only requires you to "climb the ladder up to 12 ft high" and you are perfectly fine with the average performance, handling and mediocre MPG resulting from the recommended door sticker pressure of 32 PSI. This pressure gives you all around average results on everything and it's great when your Fit is simply an A to B means of transportation, without any other aspirations.

None of the people driving on higher pressures are pushing others to do so as well. We are simply recording and sharing our experiences and results with the FitFreak community. Obviously if you are like most people, distracted 90% of the time between text messages and day dreaming, then higher pressure may not be for you.

My style of hyper-attentive eco driving (most of the time) seems to benefit in overall performance, handling and MPG when I "climb the ladder up to 20 ft high" aka 44 psi.

When I drive a car at regular "door" PSI, it reminds me a bit of riding skateboards on crappy asphalt on hot summer days.


PS:
One of the other reasons, not mentioned in this thread, that 32 PSI is being recommended by almost all car manufacturers are the cheap no-name tires that are only rated up to 35 PSI max. The one thing that the car manufacturers can't control is what crappy cheap tires the owners are willing to put on their cars, which can create liability for the car manufacturers if they were recommending higher pressures.
 

Last edited by Andrei_ierdnA; 03-06-2018 at 12:02 AM.
  #262  
Old 03-05-2018, 01:48 PM
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your sig says 35.7 mpg. with all that hardcore eco driving you only net 35.7? lol

i could easily do 42mpg without trying running 35-36psi on my GK.. and i could careless about mpg. imaging someone who cares behind the GK’s wheel..
 
  #263  
Old 03-05-2018, 02:11 PM
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Originally Posted by kenchan
your sig says 35.7 mpg. with all that hardcore eco driving you only net 35.7? lol

i could easily do 42mpg without trying running 35-36psi on my GK.. and i could careless about mpg. imaging someone who cares behind the GK’s wheel..
At least my 35.7 mpg is based on honest measurements recorded over 120 fuel-ups through all sorts of different driving conditions.
Your supposed 42 mpg is only a fart in the wind until proven otherwise...

I don't know where you live, but up here in the Great White North, I have to drive through long & bitter cold winters, using snow tires and winter gas, all of which significantly reduce fuel mileage. In the mornings I leave the engine idling for a few minutes, while I scrape the windshield from the overnight ice that tends to happen in the winter, regardless of precipitation, from November 'til April.
About 50% of my driving is in the city, with short trips, red lights, pedestrians & traffic. Also my commute to work is only 10 miles (16 km) each way of mixed city/hwy, so the engine barely operates truly efficient during my daily commute.
Lastly, I drive a manual Fit, which revs higher than an auto at pretty much all speeds.
And the Fit is fun as hell to rev high.

Since the EPA rates my car at 33 mpg highway and 29 mpg combined, I'm doing great beating the EPA by over 20% in combined mileage, given my driving conditions.
https://www.fueleconomy.gov/feg/bymo...onda_Fit.shtml

As long as you keep comparing your oranges to my apples, your opinion will be completely redundant.
 

Last edited by Andrei_ierdnA; 03-06-2018 at 12:08 AM.
  #264  
Old 03-05-2018, 07:16 PM
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Originally Posted by Andrei_ierdnA
At least my 35.7 mpg is based on honest measurements recorded over 120 fuel-ups through all sorts of different driving conditions.
Your supposed 42 mpg is only a fart in the wind until proven otherwise...

I don't know where you live, but up here in the Great White North, I have to drive through long bitter winters, using snow tires and winter gas, all of which significantly reduce fuel mileage. In the mornings I leave the engine idling for a few minutes, while I scrape the windshield from the overnight ice that tends to happen in the winter, regardless of precipitation. This overnight windshield icing happens all the way from November until April and sometimes into the first week of May.
About 50% of my driving is strictly in the city, with lots of red lights, stop signs, pedestrians & traffic. Also my commute to work is only 10 miles (16 km) each way, so the engine barely operates truly efficient by the time I reach my destination. Lastly, I drive a manual Fit, which revs higher than autos at pretty much all speeds, and the Fit is fun as hell to rev high.
Even eco drivers like to have fun behind the wheel (at least the ones driving stick shift cars).

Since the EPA rates my car at 33 mpg highway and 29 mpg combined, I'm doing great beating the EPA by over 20% in combined mileage, given my driving conditions.

https://www.fueleconomy.gov/feg/bymo...onda_Fit.shtml

As long as you keep comparing your oranges to my apples, your opinion will be completely redundant.
which part of i could careless about mpg did you not read in my post? think bigger. saving a few bucks here and there with all that effort is a waste of time. get a real job and drive like you want. want to save a tree? ride a bike.

that 42mpg is real. i calculated milage by the gallons i put in. my GK is my wife's car so i usually dont drive it much, but the few weeks she wasnt around i used the car for the commute it was showing 43mpg+ ill leave it there. GL
 
  #265  
Old 03-05-2018, 07:53 PM
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Originally Posted by kenchan
which part of i could careless about mpg did you not read in my post? think bigger. saving a few bucks here and there with all that effort is a waste of time. get a real job and drive like you want. want to save a tree? ride a bike.
Not carrying about mpg means you're likely 'merican, since your gas is cheaper than bottled water.

Saving a few bucks here and there is exactly the approach of most self made millionaires.
Wasting a few bucks here and there is the approach of the middle class (the ones living perpetually in debt) and the poor.
Sure the fuel savings are pocket change in the grand scheme of things, but it's still $$$ I'd rather keep in my pocket than ignorantly handing it over to gas companies. To each their own. The 20% I save over EPA ratings is definitely not to be pissed away.
And what exactly is "all that effort"?
I really don't see the effort, nor the wasted time... unless you mean the great effort of waiting around that extra minute it takes to pump the tires up to 44 psi. What a bunch of wasted time

By the way, I do have a real job.
Actually, what is a real job? Maybe mine is unreal and I just hadn't realized it.
"...and drive like you want" = wtf ?
No need to talk about trees or bikes, it's a car forum and we're all drivers here.

Originally Posted by kenchan
that 42mpg is real. i calculated milage by the gallons i put in. my GK is my wife's car so i usually dont drive it much, but the few weeks she wasnt around i used the car for the commute it was showing 43mpg+ ill leave it there. GL

Congratulations I suppose.
I'm still not that impressed, as there's no proof here; a few weeks of driving isn't statistically significant.
I'd be interested in knowing what your daily commute was like.
If you got 40+ mpg driving 10 miles each way of 50%city-50%hwy in freezing temperatures and rolling on winter tires, then you've completely convinced me to change. I will think bigger, start wasting a few bucks here and there, and stop wasting time with all that effort. I will get a real job and drive like I want. Obviously then I'll also reduce my tire pressure to whatever you're using and I'll stop carrying about mpg. Hopefully that's the recipe to 40+ mpg...not that I care
 

Last edited by Andrei_ierdnA; 03-06-2018 at 12:46 AM.
  #266  
Old 03-06-2018, 04:36 AM
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Over the years, and even at different automotive sites, with different vehicles, I've learned I'm not going to convince somebody that believes running higher PSI that it's better just to follow the MANUFACTURER of the vehicles recommendation.

But I think it is best. MPG gains at higher PSI, seem at best minimal, at worst totally chimerical. Not worth the harsher ride and possible negative affect to the suspension.

I'm convinced those that ignore the advice are mostly just blinded by the "fun" of thinking they've discovered a better way or better "sweet spot". I'm convinced whatever Honda recommended...they would do different.

Nobody has ever been able to convince me it actually is better.
The very minimal, possible MPG gains the lower rolling resistance of a IMO over inflated tire creates are not worth the risks of driving a vehicle with the tires PSI out of manufacturers recommend spec's.
They are not created on a whim. Every manufacturer wants to advertise the best possible MPG for the vehicle.
If running 5-10-15 PSI higher was "better"-overall....that would be the recommendation. It is NOT.
 

Last edited by fitchet; 03-06-2018 at 08:59 AM.
  #267  
Old 03-06-2018, 09:11 AM
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Originally Posted by Andrei_ierdnA
Saving a few bucks here and there is exactly the approach of most self made millionaires.
Wasting a few bucks here and there is the approach of the middle class (the ones living perpetually in debt) and the poor.
IMO short sighted stereotype's of both classes.

Really in admittedly minimal experimentation, I have found higher PSI...really doesn't result in any amazing MPG gains.

Balance that "savings" against possible instability on the road, premature wear and damage to suspension components, and I think the tangibly dangerous scenario, of tires set to the max the tire is made to handle as opposed to the recommendation of the manufacturer and designers of the automobile....
And one blow out, one decreased stopping distance accident...and all that "savings" goes right out the window, in perhaps a tragic manner.

That's impotently trying to be penny wise, but being PSI foolish.
 
  #268  
Old 03-15-2018, 01:35 PM
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Originally Posted by fitchet
The very minimal, possible MPG gains the lower rolling resistance of a IMO over inflated tire creates are not worth the risks of driving a vehicle with the tires PSI out of manufacturers recommend spec's.
They are not created on a whim. Every manufacturer wants to advertise the best possible MPG for the vehicle.
If running 5-10-15 PSI higher was "better"-overall....that would be the recommendation. It is NOT.
Absolutely the MPG gains are minimal. At most one can hope to see about 5% if inflating from 32 psi to 44 psi.
IMO 5% is a decent ROI in this economy.

It's been said many times that manufacturer's recommend 32 PSI for comfort, which is one of the more important factors for most people when choosing a car. Especially when considering how much of the population is either over-weight and/or old, suffering from a bad back, hemorrhoids, arthritis, etc. None of those people would even trade comfort over improved handing and MPG gains.

If manufacturers would recommend higher tire pressures, they would have to soften the suspension to reach the same comfort level, which will increase body roll in corners and nobody likes that.

Also many people are misunderstanding over-inflation.
Over-inflation = going beyond the max sidewall pressure (44 psi or 51 psi for other tires).
Over-inflation does NOT mean going anywhere in the normal operating tire range of 32 psi to 44 psi.

Originally Posted by fitchet
Really in admittedly minimal experimentation, I have found higher PSI...really doesn't result in any amazing MPG gains.

Balance that "savings" against possible instability on the road, premature wear and damage to suspension components, and I think the tangibly dangerous scenario, of tires set to the max the tire is made to handle as opposed to the recommendation of the manufacturer and designers of the automobile....
And one blow out, one decreased stopping distance accident...and all that "savings" goes right out the window, in perhaps a tragic manner.
That possible instability on the road is honestly not the case. Under-inflated tires will cause real road instability and blow-outs.
Blow-outs also do NOT happen from tires inflated at higher pressures (up to tire max). If you do some research you will find that blow-outs almost always happen either when the tire is too old (rubber falling apart) or when the tire is under-inflated causing high friction -> high temperatures -> rubber starts to deteriorate rapidly -> ka-boom

Earlier in this thread one of the members reported having "stepped" on a nail with tires over-inflated somewhere in the 60 PSI range and he did not have a blow-out. Not only that, but he got cheap tire hole fix and kept riding those tires up to 80 PSI without any blow-outs at all.

So on one hand we have people offering honest reviews based on real life experience and on the other hand we have people spewing fear-mongering based on misconceptions or hear-say. I'll stick to the first group, but that's just me.
 

Last edited by Andrei_ierdnA; 03-15-2018 at 01:59 PM.
  #269  
Old 11-01-2019, 05:15 PM
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Originally Posted by mahout
The coefficient of expansion of nitrogen is less than that of oxygen so the pressure increase is less.
Its only significance is in racing where heat buildup is extreme (on the order of a hundred degrees or more) and critical to the tire not overpressurizing, losing valuable contact surface.
I've forgotten what the optimum tire temps for GY race tires but it seems that it was around 220 degrees F.
Using nitrogen on the street isn't much of a help in mpg where higher pressureis the item that increases mpg.
The single useaful thing about nitrogen is that bleedout of the pressure through the tirewall (what you thought they are impervious?) is slower with nitrogen because the nitrogen molecule is larger and harder to permeate through the rubber.
Sorry nitrogen and oxygen and air all follow the ideal gas law PV=nRT so if the n number of molecules are the same and the temperature is the same- the pressure remains the same at the Same volume. R is a universal constant.

Nitrogen is just fancy and an upcharge at service stations.
 
  #270  
Old 06-23-2021, 09:00 AM
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I agree with this
 
  #271  
Old 08-07-2021, 07:25 AM
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Really useful info
 
  #272  
Old 08-10-2021, 05:55 PM
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I have been inflating my tires to 36 psi, instead of 32, because the handling feels slightly better. I have not experimented with higher pressures, because I didn't want to stray too far from the recommended pressure from Honda, although I have considered trying 38 just to see what its like, not for the fuel economy.
 
  #273  
Old 05-21-2022, 06:35 PM
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1. Stock eco-tire look
2. Height from the ground
3. Rear brakes are drums, not discs
4. The seat only moving forward-backwards and not up-down, makes it semi uncomfortable for non-japanese drivers

All in all, pretty minimal complaints if that's the extent of my disappointment.
 
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