Lockedwill taller tires help your gas mileage?

Post
400kodiakodish
Mud Slinger
2005/08/20 15:04:39
Alot of people I know run taller tires to keep there Rpms down. While I can see that if you are turning the engine a little less that less fuel will be burned. However when tires get taller they in turn ususally get heavier, wouldn't the increase in weight delete any advantages a taller tire had as far as fuel economy? I'm saying like going form a 245-75-r16 to a 265-75-r16.
bigrubicon2003
Mud Master
Re: will taller tires help your gas mileage? 2005/08/20 15:18:23
i went from a 235/75/16 to a 305/70/16 and it killed my gas mielage.
bluekodiak450
Mud Master
Re: will taller tires help your gas mileage? 2005/08/20 15:27:28
when you get bigger tires the engine has to work harder to turn them which means that it gets worse gas milage
DIRTYLILMAN
Mud Bogger
Re: will taller tires help your gas mileage? 2005/08/20 15:58:58
Bigger tires act like similarly to gears. At highway speeds you are going to see an increase in gas mileage, in city driving you have to get those big meats turning so it will burn more fuel and take more power. If you drive a lot of highways miles, the larger tires will net you better gas mileage.
fourtrax_300
Mud Pro
Re: will taller tires help your gas mileage? 2005/08/20 16:48:26
there is more rolling mass to a biger tire and it takes more time and more power to get a full rotation of them campared to a smaller stock tire
DIRTYLILMAN
Mud Bogger
Re: will taller tires help your gas mileage? 2005/08/20 18:23:22
The bigger tires once turning have more enertia and wont slow as quickly as a smaller tire, so on highway they get better mileage. Larger tires will usually last longer also.
dcastlewood
Trail Rider
Re: will taller tires help your gas mileage? 2005/08/21 01:52:32
Get the bigger tires, gas is free...right?
Re: will taller tires help your gas mileage? 2005/08/21 11:28:55
You have to factor in everything, Bigger tires cause the motor to work harder. however most people don't figure out compounts, width's or anything. If you go from a 30 inch to a 33 inch tire, narrow and hard as a rock your millage will go up. if you go to a wider, softer, taller tire it will go down as the rolling resistance is greater. There's a reason 18 Wheelers run such tall tires. Tall, hard, and they revolve less which makes them last longer. In most cases of lifts, and soft tires, you'll do much worse. Who drives a lifted truck easyier = )
DPB
Mud Maniac
Re: will taller tires help your gas mileage? 2005/08/21 14:31:43
taller tires will kill mileage.
bruteboy
Mud Monster
Re: will taller tires help your gas mileage? 2005/08/21 20:25:23
Im with DPB. And on the highway you wont get any better mileage because the odometer is off because there is less revolutions of the tires. It will take more HP to turn the tires and it will take more gas to do so.
DIRTYLILMAN
Mud Bogger
Re: will taller tires help your gas mileage? 2005/08/21 21:28:38
Its not a matter of opinion, if you go from a 29" tire to a 33" tire you WILL get better gas mileage on the highway.
jaysbad400
Mud Master
Re: will taller tires help your gas mileage? 2005/08/21 21:51:15
can you go little bigger than 265 70 R17 on a 2005 yukon 4x4 with bf good rich allterrains
HELLFIRE
Mud Maniac
Re: will taller tires help your gas mileage? 2005/08/22 11:05:30
Quote:

The bigger tires once turning have more enertia and wont slow as quickly as a smaller tire, so on highway they get better mileage. Larger tires will usually last longer also.




???????????? That makes no sense at all. Taller tires in no way last longer. If I run a 44" Bogger and John doe runs a 31" BFG all terrain the BFG will outlast that tire all day long. Size of tire has nothing to do with wear.

Bigger tires will not help in gas mileage at all. It all revolves back to the fact that it takes more energy to move. More energy means more gas.
HELLFIRE
Mud Maniac
Re: will taller tires help your gas mileage? 2005/08/22 11:24:44
Quote:

There's a reason 18 Wheelers run such tall tires. Tall, hard, and they revolve less which makes them last longer.




That is the dumbest thing I have ever heard.

18 wheelers use bigger tires to support the weight. The tire has to be much thicker than a passenger car tire. They have to have a sidewall that tall to hold up the loads they have to carry.

No matter what you say it takes more energy to move a bigger tire. Energy is made by gas. do the math.

Yeah you may have more rolling mass. Does that mean you can get to 70 on the interstate and let off and keep rolling 70? No! It is Physically impossible for a bigger tire to get better gass milage. I do not drive my truck hard. It is a street queen. In Town Milage = Worse. Highway Mileage = worse.
The_Law
Super Swamper
Re: will taller tires help your gas mileage? 2005/08/22 13:00:07
Simple answer: It depends on many variables.
Tank
Mud Master
Re: will taller tires help your gas mileage? 2005/08/22 15:20:52
It depends. Mileage will incease if you have enough torque that the motor does not know the tires are there. i.e. my dads d-max making about 650lb/ft milege went up going from a 245 to a 285. There is a happy medium in there where the tire can get just to the point that the truck doesn't have to use anymore fuel than it would on a smaller tire. If the power is already there, use it.
Guest
Outlaw Extremist
Re: will taller tires help your gas mileage? 2005/08/22 15:45:52
they covered this on "trucks" one sunday. in a nutshell, in theory, the taller tire will get you better gas mileage because of highway speeds. you have to go 60 or 70 mph ALL THE TIME, which will never happen, to make the theory work. in the real world though, you work twice as hard getting up to highway speeds, and with city driving factored in, you loose in the end.
DIRTYLILMAN
Mud Bogger
Re: will taller tires help your gas mileage? 2005/08/23 21:32:16
Hellfire, those two posts have to be the most ignorant posts that I have ever read by you, are you sure you typed them? First of all, for any kind of comparison all things need to be hel equal. Meaning you cant compare a bogger to an all terrain regardless of size. I will guarantee that a 33" bogger would get worse mileage than a 33" bfg a/t. Your also wrong on the fact that a larger tire will wear the faster than a smaller tire. Again all things held equal a larger tire will last longer than a smaller tire. If YOU do the math, since you seem to be such the scientist, you would see that a 40" tire compared to a 33" tire would net an approximate 18% increase in tire life, so if your 33" tire lasted 35k miles a 40" tire would last 41300 miles. This is however not taking into account a lifted truck that you would need to run the 40" tires its jsut an example to show the difference in tire life with a larger tire. Also, some people drive a lot of highway miles, if you are one of those people then the larger tires will increase your gas mileage. If you compared a 33" tire to a 29" tireand your driving 70 mph your speedometer will be about 10 mph off. This is because your larger tires are rotating less than your smaller tires, this translates into lower engine rpm. It equates similarly to putting gears into your vehicle, with 3.73's you are going to get better highway mileage as opposed to a 4.56 gears. Your 4.56 gears are going to get your tires moving easier than your your 3.73's which will take less engine power at the start, once your up to speed however your going to running at a higher rpm. Its not rocket science so there is no need to bash on someone elses post when frankly they are right and well...you are not.
Re: will taller tires help your gas mileage? 2005/08/25 13:12:47
Exactly there are so many variables. if your running a tire with durometer of 50 (spelling) and have a 30 inch tire and a 40 inch tire, the 40" will last longer. This is due to the fact that the 30 inch tire has to turn twice to equil once of the bigger tire (approximatly) So if everything was the same yes it would last longer. However when you compare tread compounds, hardness, width's, weight of a truck, driving habbits, ect, it changes big time. Normally tires do need to be bigger to accomidate weight and increased side walls, but also the taller the tire the more miles an 18 wheeler will get. Imagine if they ran 30 inch tires, they'd replace them every 10,000 miles with the weight that's on them.

Also there are no stupid posts. The only stupid post is somebody that dosn't post a question cause there too high strung on them selfs. And there's always more than one right answer, and way to do something. I don't know much about 18 wheelers and all that (I do work as a Biotech Pharmicuitical Engineer) and can tell you what, why, and how each strand of DNA in your body works, but some stuff is strange to me also.
gotmuddy
Respected Member
Re: will taller tires help your gas mileage? 2005/08/25 14:13:33
Here is how I see it. When a car maker puts tires on a truck they factor lots of things in, and nowadays fuel mileage is big. A truck designed to run a 30" will get best mileage with a 30" tire. This is talking about gas engines of course. To me its just common sense that a truck designed to run a certain size tires gets the best mileage with those tires. There are a few variables however. If you have an old truck with 4.56 gears and it winds out at 60mph then going to bigger tires will help. Other than that, you will only be hurting your mileage. I think on diesels, bigger tires dont affect mileage as much as gas trucks.
HELLFIRE
Mud Maniac
Re: will taller tires help your gas mileage? 2005/08/26 10:51:22
Quote:

Hellfire, those two posts have to be the most ignorant posts that I have ever read by you, are you sure you typed them? First of all, for any kind of comparison all things need to be hel equal. Meaning you cant compare a bogger to an all terrain regardless of size. I will guarantee that a 33" bogger would get worse mileage than a 33" bfg a/t. Your also wrong on the fact that a larger tire will wear the faster than a smaller tire. Again all things held equal a larger tire will last longer than a smaller tire. If YOU do the math, since you seem to be such the scientist, you would see that a 40" tire compared to a 33" tire would net an approximate 18% increase in tire life, so if your 33" tire lasted 35k miles a 40" tire would last 41300 miles. This is however not taking into account a lifted truck that you would need to run the 40" tires its jsut an example to show the difference in tire life with a larger tire. Also, some people drive a lot of highway miles, if you are one of those people then the larger tires will increase your gas mileage. If you compared a 33" tire to a 29" tireand your driving 70 mph your speedometer will be about 10 mph off. This is because your larger tires are rotating less than your smaller tires, this translates into lower engine rpm. It equates similarly to putting gears into your vehicle, with 3.73's you are going to get better highway mileage as opposed to a 4.56 gears. Your 4.56 gears are going to get your tires moving easier than your your 3.73's which will take less engine power at the start, once your up to speed however your going to running at a higher rpm. Its not rocket science so there is no need to bash on someone elses post when frankly they are right and well...you are not.




Where did you read this equasion you came up with for tire wear? I want to see it. If there is only that difference in wear it is because a larger tire's tread depth, in most cases, is deeper. Hence more tread to wear.

I see what you are saying about revaloutions of the tire and such. You say the smaller tire makes more revolutions. We make Speedo correction units for trucks so i deal with this all the time.

My deal with the gass mileage thing is the tire weighs more. Therefore it takes more entergy to get moving and keep moving. Yes if every road on earth were flat this would make sence. But every time you encounter a hill your engine has to get that heavier tire moving back to that speed.

Take this into consideration. If a Larger tire got better gas mileage. Why has the EPA not make car makers start increasing tire size? They would essentially be helping their gas mileage. You also have to figure in the wear on other components like a transmission, rear end, u-joints etc... when you dont install gears. If you managed to achieve any kind of gain in mileage on the highway it would be completely wasted as soon as you exited.

It all boils down to weight. More weight takes more entergy to move. Take a Ford Focus and put a Foucus motor in a Superduty. Which one will get better mileage? Going by the info most people have posted here Im going to go order a Superduty with a Focus motor to save gas.
gotmuddy
Respected Member
Re: will taller tires help your gas mileage? 2005/08/26 12:30:54
Another thing to consider is that unless you live in the desert you can't drive highway speeds on all highways. Heck, around here you cant safely drive 55 on most roads. The nearest 70mph road is 1.5hrs away.
DIRTYLILMAN
Mud Bogger
Re: will taller tires help your gas mileage? 2005/08/27 17:36:50
The equation that is used is circumfrence=2?r. Its basic geometry, I am guessing you aren't working in the engineering department of superlift, if so Im scared. A larger wheel of any kind is going to wear less than a smaller wheel because it rotates less than the smaller wheel will. It has absolutely nothing to do with weight. You need to put things in perspective, you are comparing two tires that are of similar size. To get a better idea compare two things of extremely unequal size but made of similar properties. Now think of inertia and momentum, logically you would think that a larger heavier object would slow faster than a smaller light weight object. Not so in most cases, compare a marble to a boulder, say I roll it down a 15 incline that is 100yds long and then goes to a zero incline thats an infinite distance. Which object is going to roll further? As I stated and another member stated, once in motion objects do not stop unless other forces act on them: friction, gravity, etc. So once you get those big wheels turning it doesn't burn any more fuel to keep the larger wheels rolling than it takes to keep the smaller wheels rolling. Its called conservation of momentum, its part of newtons first law. What takes the most amount of energy is always used to get the initial momentum going, after that sustaining your momentum is not a problem. If you really wanted to get technical you could factor in everything that could possibly prevent you from getting better gas mileage but it would still show that the larger tires will net you better mileage on the HIGHWAY as I stated before. There is always a trade off, its like hybrid cars, they get better gas mileage in the city when its stop and go driving and worse on the highway, but they get better gas mileage all around. Simply put as I stated before tires act the same way that changing gears do, if you want to do a comparison go to www.4lo.com and they conversion tables. I wouldn't base my argument on that of the EPA or auto manufacturers, larger tires cost more money to make, more money equals less profit. It may not seem like much but there are plenty of things that auto makers can do to make there vehicles get better gas mileage, but its a tradeoff, newer technology costs more money, if manufacturers spent another $100 on every car they make to conserve fuel they would be losing 100X # of cars sold every year. When you sell 20 million cars a year thats an extra 2 billion dollars a year more to save the consumer an extra 2 gallons of gas per mile. Its not good business for them to do that. Auto makers and government bodies are influenced by money, so dont rely on that to make an argument. You should have more respect for other members especially when your talking out of your ****.
HELLFIRE
Mud Maniac
Re: will taller tires help your gas mileage? 2005/08/28 02:32:52
You are missing my point. I see what you are trying to say. But the whole thing boils down to there is just more tire to wear because it is making less revolutions. The tread does NOT last any longer because it is bigger. I also said nothing about weight making a difference in wear.

You also must not have read my other post fully or you would have seen that I do know that a taller tire can roll easier. My point is no road is compleatly flat. At some point more entergy is going to have to be used to get that tire moving back to speed. At that point what ever you may have saved on a flat section just got burned up. Any time you apply preasure to the gas to accelerate, gain speed or keep your same speed it is having to use more power. Unless you punch it on the downhills and hope to coast up the other side.

Also 99% of the time when you go with a bigger tire it is wider. Wider means more drag. More drag means it will need more power to move. More power means more fuel. Think of a bike. A Mountan bike with the same height tires as a road bike takes more power to get moving. it also slows faster when you stop pedaling. Why do you think Road bikes have skinny tires?
PRAIRIEMAN
Mud Master
Re: will taller tires help your gas mileage? 2005/08/28 11:42:03
Bigger tires=worse gas mileage, I don't care what anybody says.
Mindgame
Mud Bogger
Re: will taller tires help your gas mileage? 2005/08/29 17:14:52
Short answer: no

There's a compromise to everything. The basis of it all starts at the point on the road: the contact patch. Any time you go to a taller or wider tire, you increase the area of contact. Now, the gound pressures on this contact area isn't like a uniform distributed load on the ground, it is shape more like a very tall "bell curve". Since the friction coefficients for most road tires are close to the same, increasing this area means more resistance (bad for gas milege). Keep in mind that there is more than just one type of inertia, as the motion of a rolling tire is classified as "general plane motion". This means that the tire has both rotational and translational moment of inertia. A taller tire has greater rotational and translational MOI, so any change in rotational speed will mean more force or work is required to rotate the tire (bad for gas milege). A taller tire also reduces your effective gear ratio, meaning you have less torque multiplication, so the engine has to work harder to turn the tires (bad for gas milege). And considering that an engine will get it's best gas milege at its peak volumetric efficiency (i.e. at its peak torque rpm range) and larger tires will reduce your rpm at any speed on the highway, taking it further from peak VE range.... yep, bad for gas milege.

But the compromise on the other side of the fence includes lower rpm (remember this?). This means the drivetrain parts make fewer rotations and at a lower speed, meaning less frictional losses through them and less wear. That's about all there is good about taller tires.

Manufacturers have to make a compromise between milege, parts wear, and cost to equip these vehicles to achieve these fuel efficencies for sale to the public. Believe me, they do whatever they can to cut costs.

As for the "18 wheeler" comments, they have to keep ground pressures on the pavements to a certain maximum value. In fact, the FHWA has mandated a maximum GVWR of 40 tons (80,000lbs) for these 18 wheelers so that the highways can last to their intended service life. I can't spit out a ground psi figure for you, but if we estimate that each contact patch to be 10 square inches, then 80,000/(18*10) is around 445psi. I think one of my colleages has said a max of 7-800psi at peak pressue (center of contact patch) is acceptable, since the loading on these trucks is never symmetrical. And taller tires also means less wear on parts for these high-milege runners... replacing tires more often is cheaper than fuel costs and parts costs in the long run.

My $.02
Tank
Mud Master
Re: will taller tires help your gas mileage? 2005/08/29 19:31:41
With the big rigs though you have to keep in mind that it isn't just the pressure but how far the pressure is spread out. That is why the DOT mandates things like dollys, spreaders, and jeeps. When we transport our 330LBX we have to use a tri-axle low boy with the tag axle down on the truck, we come in right at 113,000lbs. and they charge about $180 for a one week, in county permit. Now when transporting a D10 or 365 track machine the truck setup is slightly different, but we won't get into that. Oh I do underground utilities and dirt work, that's why we move this stuff.
Mindgame you seem very knowledgable, what field of work are you in?

Edit: Don't forget about the weight spread for bridge laws either.
Mindgame
Mud Bogger
Re: will taller tires help your gas mileage? 2005/08/29 20:26:59
You are correct, and from what i remember back in my CivE days, the loading i pointed out earlier was from the standard 18 wheel configuration. 40 tons+ means more axles are needed since that "magic" figure of 7-800psi under each tire can not be surpassed. I can understand for asphaltic pavements, but they are just as crazy about concrete pavements too, even though the concrete the DOTs use are at least 4000psi compressive strength.

Was a civil engineering tech for a couple of years then decided to go to college for a BSCE. Lost interest in it after getting a few semesters into the curriculum then changed career paths to automotive engineering. I hope you can understand, I can't say who my employer is as i must remain incognito for business reasons.
Spacecwboy
Mud Master
Re: will taller tires help your gas mileage? 2005/08/29 20:42:09
larger tires (or taller tires dont last longer) case in point: I have a set of 20's on my 05 chevy supercrew v-8, It is WELL known that 20's wear quickly. Lots of people have made good points and lots have made ignorant points. A larger tire takes more force to move it (a larger tire is heavier) therefore it takes more to KEEP it going. If larger tires tires were that effective you would see ford festiva's on 38's.
gotmuddy
Respected Member
Re: will taller tires help your gas mileage? 2005/08/30 09:14:23
Big rig tires last alot longer than your average car/truck tire. Expect to get 130k out of one tire before having it resurfaced.
Tank
Mud Master
Re: will taller tires help your gas mileage? 2005/08/30 11:10:12
I'm guessing one of the Big 3, but I'll leave it at that.
Mindgame
Mud Bogger
Re: will taller tires help your gas mileage? 2005/08/31 12:26:13
We started getting off track a ways up, so to try to narrow the discussion due to so many variables being thrown in other than height (original question), let's make a reference point from when the vehicle was stock with its stock tires; and by saying "taller" tires means going to a larger tire height with minor changes in width to keep the contact patch near the same area (with the same tread pattern). These constrains should make it an easier comparison.

Quote:

Big rig tires last alot longer than your average car/truck tire. Expect to get 130k out of one tire before having it resurfaced.




Very true. Ceteris Paribus conditions, a taller tire will last longer than a shorter tire (meaning same compound, tread pattern and depth, and within the same application). With a taller tire, any point on the tread will make longer contact intervals with the ground while traveling any distance.

Just to compare height defferences, take the last set of tires i had on my truck, 31" tall, which lasted me roughly 55k miles before replacement (95% highway miles). A 31" tall tire has a circum of (31/12)*(pi)= 8.11 feet. But let's account for tire expansion and contraction while rolling and say 8 feet. So every 8 feet a point on the tread touches the ground. Neglecting slippage and changes in height due to wear, each point on the tires made approximately 36 million contacts with the ground in that 55k miles. A tire with a 40" rolling distance (with the same ground pressure distribution as the 31", to keep things equal) will have contact points about every 10.5 feet apart, or about 27.6 million contacts in 55k miles. For the 40" tire to make 36 million contacts, it would have to travel about 72k miles. So a 29% increase in rolling distance made a 31% difference in contacts. While not the only factor in longevity, it's certainly a large part of it. The engineers behind the manufacture of motor vehicles have already crunched all the numbers and performed many tests to select the tire size and pattern they did from the factory [cost (BIG FACTOR!!!) vs fuel efficiency vs performance vs longevity of both tire and vehicle, application, contracts, availability, etc], so it is a good place to reference from.
DIRTYLILMAN
Mud Bogger
Re: will taller tires help your gas mileage? 2005/08/31 18:43:51
Wow, someone that knows some math also. Try not to use latin though it confuses the readers. Heres a link that shows how much energy is wasted from what is produced.

http://www.fueleconomy.gov/feg/atv.shtml