Increase mpg just by pumping up tyres

[philepo]

tyre pressure semi-facts

Thanks for all the feedback, interesting.

I would say that for a gentle driver (me) with tall tyres than overinflation by 10-20 % is no big deal. And I definately see a 10% decrease in fuel consumption on my regular commute pounding up the dual carriage way.

But for a fast driver and/or with low profiles this is not a good idea - fast drivers make the tyres heat up and push up psi further (which is why race cars run low cold psi).

If you are aggressive and have high psi you will decrease your grip level and hence increase wear rates.

Rgs, P

 

[DITTRICH]

I keep my tires at the upper limit (AMG 17'' alloys staggered 245/40/17 and 225/45/17).
The ride is rather harsh but there are benefits to fuel economy on long distance travelling as my trips to Russia have verified. The main things I have found to affect economy are:-

1 Speed (economy is lower in Germany and higher in Lithuania and Latvia)
2 Tires pumped up (less deformation = less energy used)
3 Keeping the AC off (difficult in summer)
4 Avoiding Kickdown (difficult on Poland's single carriageway roads)
5 Not carrying loads of heavy crap in the boot (except my tire compressor and trolley jack 'cos I'm a lazy middle aged git!)
6 Strangely I feel keeping the car polished and clean on the outside but no data to support this.

I have never experienced my tires wearing out at the centre but the fronts routinely wear the outer shoulders (cornering speed affects this).

My 2c as usual.

 

[kwakdonut]

My 2c as usual.

That's ok, that's what forums are for!!

 

[gkerr4]

I keep my tires at the upper limit (AMG 17'' alloys staggered 245/40/17 and 225/45/17).
The ride is rather harsh but there are benefits to fuel economy on long distance travelling as my trips to Russia have verified. The main things I have found to affect economy are:-

1 Speed (economy is lower in Germany and higher in Lithuania and Latvia)
2 Tires pumped up (less deformation = less energy used)
3 Keeping the AC off (difficult in summer)
4 Avoiding Kickdown (difficult on Poland's single carriageway roads)
5 Not carrying loads of heavy crap in the boot (except my tire compressor and trolley jack 'cos I'm a lazy middle aged git!)
6 Strangely I feel keeping the car polished and clean on the outside but no data to support this.

I have never experienced my tires wearing out at the centre but the fronts routinely wear the outer shoulders (cornering speed affects this).

My 2c as usual.

Hmm - this is good to know - I have the same size tyres and wheels as you (a W204 'sport') which I only got recently. I notice the tyre pressure sticker in the fuel flap - but it has quite a large range - I forget the actual figures right now as I'm in the office, but also the range is in two parts - one for low speeds and one for high speeds. I think the range for the rear goes from 32 to 42PSI - which is a massive difference but the upper range doesn't seem "that" high a pressure.

are you saying you run your car at the top of the high speed pressure range? - that gives PSi figures closer to what I would expect on this car with these tyres but I have been afraid to put them at that pressure in case it buggers anything up - is it OK to do so?

 

[Aoraki]

Just one thing........ over inflating your tyres must increase the circumferance, yes? OK then, increased circumferance must then throw out odometer by a percentage, yes? Not by 10% perhaps (OP's % saving on fuel) but something to consider..

 

[Bobby Dazzler]

Just one thing........ over inflating your tyres must increase the circumferance, yes? OK then, increased circumferance must then throw out odometer by a percentage, yes? Not by 10% perhaps (OP's % saving on fuel) but something to consider..

I don't think it would TBH, as that would imply that inflating the tyre by a few more PSI would stretch the tyre, and it wouldn't.

 

[Aoraki]

I don't think it would TBH, as that would imply that inflating the tyre by a few more PSI would stretch the tyre, and it wouldn't.

Yes it does! Tyres are not solid steel bands, there is SOME give, not much admittedly but some.

PS. one over or under inflated tyre can cause cruise control, abs etc to play up. If there wasn't a differencial in circumferance, how do you explain how my W212 knows if I have an under inflated tyre?

 

[iscaboy]

PS. one over or under inflated tyre can cause cruise control, abs etc to play up. If there wasn't a differencial in circumferance, how do you explain how my W212 knows if I have an under inflated tyre?

effective radius.

an under-inflated tyre deflects more, effectively reducing its radius and increasing rpm for a given speed.

at 60 mph tyres look more like a 50p piece than a coin

the steel / etc bands prevent over inflated tyres from expanding like balloons though

 

[Rory]

effective radius.

an under-inflated tyre deflects more, effectively reducing its radius and increasing rpm for a given speed.

at 60 mph tyres look more like a 50p piece than a coin

the steel / etc bands prevent over inflated tyres from expanding like balloons though

That's an interesting picture, but it's taken at 173MPH and no mention of tyre pressure.

I can't imagine changing tyre pressures a couple of pounds, as the OP is, makes any reliable difference - most pressure gauges probably aren't that accurate. Tests in the US on cars with very under-inflated tyres have revealed surprisingly little increase in fuel consumption.

 

[DITTRICH]

@Rory
I note your assertion that tire pressures in the USA were found not to overly influence fuel consumption. I always thought that the USA tended to use very hard rigid tires and that was why their cars had such soft suspension as any tv car chase will demonstrate. A more rigid tire would not deform so much and any under inflation effect would be less in the USA. I don't have any data to back up my theory though. I would agree that pumping the tire up wouldn't really affect its circumference by any significant amount.
Les

 

[whitenemesis]

Stick with the pressures recommended by MB and you wont go far wrong

 

[Bellow]

@Rory
I note your assertion that tire pressures in the USA were found not to overly influence fuel consumption. I always thought that the USA tended to use very hard rigid tires and that was why their cars had such soft suspension as any tv car chase will demonstrate. A more rigid tire would not deform so much and any under inflation effect would be less in the USA. I don't have any data to back up my theory though. I would agree that pumping the tire up wouldn't really affect its circumference by any significant amount.
Les

Currently, America is hell bent on preserving its way of life and what it percieves as its inalienable right to squander the resources of the Earth without changing their behaviour one jot. That they come out with clap trap like under inflated tyres don't affect fuel use doesn't surprise me, though Rory may be going some way toward a plausible explanation.
A certain section of the USA refuse point blank to give up on their gas guzzling autos. For proof, just look at the photoshopped photos of small cars involved in accidents. Car crushed to a pulp and barely a scratch on the trucks that sandwich it. And the brand of car a lie as witnessed by technically incorrect details such as the number of wheel studs!

While tyres don't balloon cartoon style with pressure the amount of deflection at the contact patch is unquestionably affected. And that's where the fuel is squandered.

 

[iscaboy]

Currently, America is hell bent on preserving its way of life and what it percieves as its inalienable right to squander the resources of the Earth without changing their behaviour one jot.

I've got plenty of yank friends, and your point is actually a lot truer than you may think.

Cheap, unlimited supplies of gasoline are very much the American barometer of well being and self esteem, and logical thought simply does not enter in to it.

Currently living yanks were born in the gasoline age, they know nothing else, and literally everything in their lives from the ephemeral to bricks and mortar is shaped by the fundamental unlimited access to cheap gas.

It doesn't matter how impoverished or deadbeat you are, unlimited access to cheap gas is the universal keystone of their society.

$5 per (US) gallon is like asking them to put their pre-teen daughters on the game, $9 a gallon (roughly what we are paying) means that the US as we know it, as they know it, has gone forever, and ain't never coming back... none of it.

That's more frightening to yanks than a nuclear WW3

 

[st4]

Currently, America is hell bent on preserving its way of life and what it percieves as its inalienable right to squander the resources of the Earth without changing their behaviour one jot. That they come out with clap trap like under inflated tyres don't affect fuel use doesn't surprise me, though Rory may be going some way toward a plausible explanation.
A certain section of the USA refuse point blank to give up on their gas guzzling autos. For proof, just look at the photoshopped photos of small cars involved in accidents. Car crushed to a pulp and barely a scratch on the trucks that sandwich it. And the brand of car a lie as witnessed by technically incorrect details such as the number of wheel studs!

While tyres don't balloon cartoon style with pressure the amount of deflection at the contact patch is unquestionably affected. And that's where the fuel is squandered.

Although a good old dig of the US of A is a tempting one, we need to also bear in mind how much they do give out in monetery aid. They are the wealthiest country and therefore have the luxury to buy up oil and sell it as they see fit...

Perhaps when there is a natural disaster they should not give a cent in aid if that is how they are percieved.

 

[RBYCC]

@Rory
I note your assertion that tire pressures in the USA were found not to overly influence fuel consumption. I always thought that the USA tended to use very hard rigid tires and that was why their cars had such soft suspension as any tv car chase will demonstrate. A more rigid tire would not deform so much and any under inflation effect would be less in the USA. I don't have any data to back up my theory though. I would agree that pumping the tire up wouldn't really affect its circumference by any significant amount.
Les

Tires are tries all over the world...
No special spec for "USA' tires...."same-same" as what you have in the UK.
Under inflation anywhere in the world causes edge wear, over inflation causes center wear.
28psi+/- gives a softer ride, 35psi+/- a firmer ride.
Fuel economy theoretically should improve, but too many variables in the equation to determine by how much.
USA cars had/have " soft suspensions because ride quality is favored in most cases over handling.

 

[RBYCC]

I've got plenty of yank friends, and your point is actually a lot truer than you may think.

Cheap, unlimited supplies of gasoline are very much the American barometer of well being and self esteem, and logical thought simply does not enter in to it.

Currently living yanks were born in the gasoline age, they know nothing else, and literally everything in their lives from the ephemeral to bricks and mortar is shaped by the fundamental unlimited access to cheap gas.

It doesn't matter how impoverished or deadbeat you are, unlimited access to cheap gas is the universal keystone of their society.

$5 per (US) gallon is like asking them to put their pre-teen daughters on the game, $9 a gallon (roughly what we are paying) means that the US as we know it, as they know it, has gone forever, and ain't never coming back... none of it.

That's more frightening to yanks than a nuclear WW3

I find humor in your knowledge of the USA...
With all due respect you're clueless....

Why should we pay high taxes on gasoline like the UK and Europe does...?
What has high energy taxes and VAT given back to the working man in your country?

High Euro taxes keep the dole going in places like Portugal, Ireland, Greece and Spain which if I recall are collapsing from the high rate of taxation and low rate of productivity.

What do energy prices have to do with self esteem?
If it is a barometer as you say then do the higher prices in the UK lead to a lack of well being and self esteem in the populace of your country ?

Do you realize how big the USA is and the amount of natural resources it has ?

I doubt it....typical progerssive mindset...

 

[RBYCC]

Currently, America is hell bent on preserving its way of life and what it percieves as its inalienable right to squander the resources of the Earth without changing their behaviour one jot.

Are you saying that "someone" should be able to dictate how you use what you have paid for and own ?

If I were to tell you I find utter disdain in some aspect of your lifestyle would you change?

How does the USA squander the resources of the Earth ????

Don't be ignorant, where would you (UK) be without the USA?
Educate yourself with a bit of factual history:

Britain pays off final instalment of US loan - after 61 years - Business News, Business - The Independent

Maybe you don't live in a truly free society where you have opportunity to be successful.

Your words have somewhat of a socialist leaning...

So what is wrong comrade with preserving a way of life that you have earned ??

 

[simon22]

I can see the mention of BP soon , one thing to remember the oil Rig is Britished named (BP) but tell me who runs it , USA workforce not Brits.they messed up not us Brits

My 10p worth

Where would you be if our British Army didnt back you in the stupid war.

 

[RBYCC]

I can see the mention of BP soon , one thing to remember the oil Rig is Britished named (BP) but tell me who runs it , USA workforce not Brits.they messed up not us Brits

My 10p worth

Where would you be if our British Army didnt back you in the stupid war.

Why not put your 10P toward a liter of petrol ?

The Deepwater Horizon rig is owned by Transocean a USA company.
The leasor of the rig and the rights to the well are BP, Anandarko and Mitsui.
The rig management was solely by BP.

The BP manangement over rode the Transocean tool pusher and failed to stop drilling when notified that the well became unstable.

BP testimony by CEO Hayward in front of the House Energy committee admitted to shortcuts in the way the well was being drilled.
Shortcuts ranging from a single string pipe, to an inadequate number of centering devices to pumping saltwater instead of mud were all to save money and reduce time to production.
He along with other BP officials may be facing criminal charges for blatant negligence that cost the lives of eleven workers.

I watched the minute by minute hearings..did you ?

Where would we be if the British Army didn't back us in our "stupid war"?
I assume you mean Iraq.
Not sure, probably the same place as we would have had to commit more troops to the southern Basra region.
Maximum Brit troops in Iraq was 18000 in 2003, wheres the USA had 250000 during the invasion.
USA still had 750000 active and reserve troops available for combat.

Conversely what would the outcome of world War II have been without the intervention of the USA.
How would the UK and every war damaged country rebuilt itself without American monies and technology?

I don't knock the UK, as I appreciate it.
Spent much time there in the eighties as I had an office off of the Old Kent Road in Lea Green, beyond Black Heath.

My business is international and at the time was oil related, so I have a bit of insight of geopolitical events.

Can't understand why indivuals as you are USA haters.

Blame your own political system and the social programs you have for the cost of energy and everything else you purchase.

It's not the fault of the USA.

I note that the anti American postings were started and continued by those who typically don't post anything beneficially auto related to the forum.

Why not take your political views to LBC 97.3 where the whole of London can hear you ?

Let's stay on topic as I believe most of the forum members are enthusiasts regardless of poltical views.

Grow up....don't be a hater of those who have achieved more success then yourself

 

[Bellow]

Are you saying that "someone" should be able to dictate how you use what you have paid for and own ?

If I were to tell you I find utter disdain in some aspect of your lifestyle would you change?

How does the USA squander the resources of the Earth ????

Don't be ignorant, where would you (UK) be without the USA?
Educate yourself with a bit of factual history:

Britain pays off final instalment of US loan - after 61 years - Business News, Business - The Independent

Maybe you don't live in a truly free society where you have opportunity to be successful.

Your words have somewhat of a socialist leaning...

So what is wrong comrade with preserving a way of life that you have earned ??

Geee , I feel so so stoopid.
Thank you so so so much for saving Britain and the world.
How can we possibly thank you??
And thank you thank you for re-educating me.
Clearly I have been sailing far too close to communism to be regarded as helathy..
Thank you Komrade.