Does increasing tire pressure really improve mpg?

[Quattro Pete]

Originally Posted By: surfstar
But the effort required to move your bike should get the point across! I notice when my bike tires are down a few for sure.

Yes, of course. But the difference isn't anywhere nearly as pronounced on radial car tires. That was my point.

But higher PSI does improve mpg. How much? Not sure.

 

[zanzabar]

+1 Inflating to max tire spec over car mfr spec improves mpg by a just-barely noticeable amount. I have observed this on many cars I've owned. My wife has LRR tires on her Honda and the max pressure is 51psi! I've only got those set at 45psi, which I did recently (was typically more like 38-40) and she just commented on how she's gotten more miles on her last couple tanks. You certainly do feel the bumps more though.

 

[Mr Nice]

Can you break 50 MPG in your HX ?

 

[surfstar]

Originally Posted By: LT4 Vette
Can you break 50 MPG in your HX ?

46 once. I don't hypermile and road trips I try to maintain 75 on the hwy. 12k mile average is 41-42mpg since I've owned it @ ~44psi. I was optimistically hoping for mid 40's when buying it.

 

[sciphi]

It generally does. I noticed it on my Cruze when the PSI dropped into the mid-30's from its usual 45 PSI. Then again, I track every tank.

Snow tires are about the only tires I don't pump up to near max sidewall pressure. I'll trade a few MPG's for better winter grip.

 

[hypervish]

Thanks for the responses everyone, keep them coming.

 

[eljefino]

One premise is a correctly inflated tire deforms to a rock in the road then springs back, pushing against that rock, after it's mostly rolled over it.

An overinflated tire transfers this bump up to the shock/strut, that holds it too long, and presses back down after the tire has already passed the obstacle.

This plausibly cuts fuel economy.

 

[Darren270]

I think people will believe just about anything...

 

[Texan4Life]

yes it decreases flex and rolling resistance. Not to mention effects load rating. All tire load ratings are at the max inflation psi on the sidewall.

Every tire is different that's why this info is printed on the sidewall. I run all my tires at the max psi.

 

[Vikas]

It is just physics. Tire contact patch decreases with the increased tire pressure. Here is an exercise. What is the contact area of a tire on 3000 lb car if the tire pressure is 30 psi? Now do the same calculation with 40 psi.

Whether is static or rolling, friction will depend upon the surface area of the contact.

So to answer OP, use analytics or experiments to find answers!

Answer:- Assuming perfect weight distribution (aka BMW each tire is supporting 750 lbs and therefore the contact area of the tire will be 750/30 = 25 sq inch or approximately 9x3 for a 225/50R16 tire

 

[friendly_jacek]

The linked PM test is retarded. Of course there is elevation difference between LA and Arizona. Somehow those Einsteins didn't think of that. Furthermore, radial tires don't "bulge out" with more pressure. They simply flex less.

Ask any hypermiller if there is a difference, duh!.

 

[KitaCam]

That's what I thought about the video...inflating to such extremes as they did is hardly real world experience for a daily drive...

 

[ARB1977]

I went from 32 rear 34 front to 38 rear and 40 front on my taco hard to tell about mpg but ride feels much better.

 

[Sonataman]

http://ecomodder.com/forum/showthread.ph...-tire-2721.html

 

[Mr_Incredible]

Increasing tire pressure most definitely increases MPGs. It decreases rolling resistance, enabling better/more coasting at the minimum and better MPGs at steady speed.

In the Prius community it is common practice to increase PSI's by two and test drive for a while. Repeat until the ride gets too harsh, then back down to where you like the ride best. I've settled at 40psi front/37 psi rear. It depends on how nice the roads are where you generally drive, mostly, but also you would not want to exceed the max pressure rating on the sidewall of the tire(s) in question.

Some tire/wheel combinations are not suited for high inflation pressures. They crown badly. My trucks have always had this problem. But our Prii have not. These tires remain straight across, with even wear indicators. You will have to experiment and keep track of how your own tires act.

How much better your MPGs would be is debateable, but some is better than none. Just don't be That Guy and drive around with your tires obviously deflated by 6psi.

 

[CharBaby]

I've never noticed that increasing tire PSI alone increased MPG. Although I think that increasing PSI adds to the many other tweeks that we can do to increase MPG. There are even many articles on LRR tires that don't show any increased MPG over a good non-LRR tire on the same vehicle.

I also think that...YMMV!

Tweeks! A little here, a little there!
Proper tune, tire pressure(+ 2-4 PSI), better lubes, driving style, filtration/breathing, freshly waxed vehicle can all add up, compared to doing nothing at all.

Just as, I don't think that synthetic oil alone will noticably increase MPG, adding all syn lubes(oil, ATF, Gear/TC Oil) "could" all do their small part in adding to the benefits of all the other factors mentioned.

I believe that we'd have to do many things in order to see small amounts of MPG gains.

The most MPG gains I ever noticed were on my older carb'd vehicles. With some filtration, carb tweeks, ignition timing tweeks, lubes, tire pressure etc, the MPG sucked less!

 

[david_ES2]

I run my vehicles at max psi which is 51 or 44psi year round , even on the fleet trucks (rangers/frontiers) at work

Yes its a little bit more bumpy but you dont notice after a day, tires wear evenly, traction for the twisty turns is still there even in rain,, and yes im a moderate hypermiler.

 

[CharBaby]

Originally Posted By: Char Baby
I've never noticed that increasing tire PSI alone increased MPG. Although I think that increasing PSI adds to the many other tweeks that we can do to increase MPG. There are even many articles on LRR tires that don't show any increased MPG over a good non-LRR tire on the same vehicle.

I also think that...YMMV!

Tweeks! A little here, a little there!
Proper tune, tire pressure(+ 2-4 PSI), better lubes, driving style, filtration/breathing, freshly waxed vehicle can all add up, compared to doing nothing at all.

Just as, I don't think that synthetic oil alone will noticably increase MPG, adding all syn lubes(oil, ATF, Gear/TC Oil) "could" all do their small part in adding to the benefits of all the other factors mentioned.

I believe that we'd have to do many things in order to see small amounts of MPG gains.

The most MPG gains I ever noticed were on my older carb'd vehicles. With some filtration, carb tweeks, ignition timing tweeks, lubes, tire pressure etc, the MPG sucked less!

And let's not forget different octane fuels. Which one works best for you engine(performance and MPG)?

 

[KitaCam]

Originally Posted By: Char Baby

And let's not forget different octane fuels. Which one works best for you engine(performance and MPG)?


...and BRANDS....despite the fact that Shell is a tier 1 brand, I get 1mph less than with Mobil and other brands (even Costco)...I stay with it because I get discount off the pump price by buying certain products at a local supermarket...since Oct. I try not to buy what I don't need or that have higher prices just to save some on the gas, but I've gotten as much as $1.00 off the 3.60 per gallon (for up to 20 gallons) so I save a lot more than I lose...just thought I'd mention that...