So let me just get this straight in your book going from 30" tires to 35" tires is going to increase gas mileage?!?!?! I guess I would just have to see it for myself, I ain't believing that ****.

 

^it aint gonna happen unless your the *** that goes as slow as humanly possible up a hill, and it still probably wouldn't happen... AND if you really got better mileage then lots more people would lift it for that reason


when did i ever say higher? i said steeper ...
also: key words "back in the day"
i dont care how old you are.. who the **** would go from 4.10 to 3.73 when lifting a truck anyways?

obviously you never learned what month was what number.. because last time i checked, 6 was june and august was 8...

 

let me rephrase..



common guys, he's been around since the ****in stone age, he knows his **** leave him alone...

 

It was about midnight when I posted and made you two months older than you should be. Sorry 'bout that.

Lets do it an easy way.

20" dia tire X 3.1416 = 62.832" circumferance. At 100 rpm this tire will travel 62.832 X 100 = 6283.2".

30" dia tire X 3.1416 = 94.248" circumferance. At 100 rpm this tire will travel 94.248 X 100 = 9424.8"

So if you do the math you will see the larger tire travels 50% farther than the smaller AT THE SAME ENGINE RPM. That will give you better fuel mileage. That is, unless you ram you foot in the throttle and keep it there.

BTW, your top speed will be higher at a given rpm, that is untill you run out of hp to push it through the air.

It's all physics and math and no matter what you would like you can't change physics or math.

I know we are only dealing with maybe a change from 30" dia. to a 32" or 35" but the larger tire will go farther at the same rpm. It will give better fuel mileage and the difference in tire size will not greatly affect the ability of the engine to push it through the air at highway speeds of 60 to 70 mph.

If you want better fuel mileage buy larger dia. tires with a narrower width and run 35 to 45 psi. The increase won't be great but it will be better, that is if you drive with a light foot and the mindset to drive like you want better fuel mileage

A wide tire at low pressure has a high rolling resistance but just airing it up to 40-45 psi will help on fuel mileage.

When I was in my teens and twenties fuel mileage was not what I had in mind. A 3/4 race engine with 3-2barrel carbs in a '51 Ford was fun and I used it a lot so I didn't get fuel mileage, I got fun mileage.

 

all i know is that with 35's im getting way worse gas mileage than with my 31's so im gonna have to agree with 99ranger4x4. you've missed something because the tire may travel farther but it is obviously harder for an engine to push 35's than 31's thats just common sense...

 

What ever works for you. I'll stick with math and physics to solve my problems. The over size tires will make it harder to take off and you may use more throttle to get the aceleration you were before. If you didn't change the speedo gear the big tires have you going faster than the smaller tires. So, you may be driving 10 or 15 mph faster with more wind resistance. Plus if the tires are wider and you don't air them up to the recommended max pressure the rolling resistance will be higher. If you drive hard from stop to stop and pass a lot on 2 lane roads you'll get poor fuel mileage.

You have to drive like you have no where to go and all day to get there if you want to get fuel mileage. Good fuel mileage don't just happen, it has to be planed and managed.

There is a lot of things that can cause poor fuel mileage and your foot is one of them.

 

are you really 67?

because it really doesn't seem like it....





on paper sure JUST LOOKING AT THE ROTATION OF THE TIRES then it would work.

when you go to 35s, you tend to regear the axles and that brings the engine speed back UP... and your engine has to work harder aka there goes your mileage

 

Well, changing the rear end ratio would change things. Depending on what the final ratio at the tires is determined by the circumference of the tire and the rear end ratio compaired to the original tire circumference/rear end ratio you may have raised or lowered your rpm at a given speed. That would have to be figured out mathmatically.

The wind resistance will not change with either set of tires/gear ratio at a given speed so that will not affect the fuel mileage. Also, if the large tire setup has the same foot print as the original tire setup there will be no change in rolling resistance.

What I posted was based on NOT changing the rear end. If you change the tires and rear end ratio so you end up with the engine turning the same as with the original tires at the same speed then the only factor is the rolling resistance if the tire foot print is larger on the larger tires. Even then it would not be great.

I still say your driving habits are what is causing the low fuel mileage.

My sons vehicle has tires that are 2" taller and 2" wider than original with no rear end change and he is getting about 2 mpg less than stock. He is 41 and drives a little hard, much like me. His foot print is larger than stock and he only runs 32 psi.

No, I am not 67, I am 66, 5 months and 7 days.

 

if you lift a truck and keep the same width tires... especially 35s.. ew

 

Well, it's true that if you lift and go larger dia. it's likely the tire will be wider and that is what most are after. Taller and wider tires with a suspension and body lift.

I can see losing 2 to 4 mpg but not many really know what they lose and I doubt they really know because they didn't keep records and their driving habits are not consistant especially young drivers. I sure didn't think much about gas mileage when I was young.

I was raised to keep records by my uncle when I worked in his speed shop.

If your going to claim a loss or gain in fuel mileage you have to have a base line to work with and the test has to be done under the same conditions. I doubt very seriously many of the young drivers here really keep records or do a quantifiable test.

That's why I don't believe some of the claims of lower fuel mileage. Have I completely explained my position.

I am not trying to be a smart ***, just pointing out issues with fuel mileage claims. Even when I do mileage tests on my trk. the weather conditions, etc. over the same road will cause differences and my mileage may vary 2-3 mpg even though I try to control the way I drive.

I am sure some of the members here are record keepers and young and their posting on mileage would be good.

EDIT: Just as you read my posts and say WHAT, I look at some posts here and like wise say WHAT. So I guess it's tit for tat.

 

wow that was intense......

 

Well, dude, to be honest with you I don't think most of the "youngins" on this site can't afford NOT to pay attention to gas mileage. I'm 19, I've been keeping mpg logs since I was 16 in my 94 C1500 Long Bed, best I ever got was 13mpgs city; 93 Accord I got 25 mpgs city; 05 Ranger started out at 17, went to 21 (lowered+intake and exhaust), down to 18 (lifted), and stayed there through 4" more lift. I know my math and my mpgs. Your logic is perfect in a frictionless world but in the real world the pavement has more leverage against the engine with big tires as it would with smaller tires. Lets say you're trying to pick up a 12lb. bowling ball in a "pool net" that's 12' long and does not bend WITH ONE HAND, I don't think you could do it. Now lets say you try to pick up that same bowling ball with a 2' dip net STILL WITH ONE HAND, much easier. Relate this to an engine and tires: an engine is trying to move 4,000lbs by moving that same line, represented by nets, across pavement. It's easier for an engine to move itself with lets say 15" of leverage against it than it is for 18" of leverage. Easier means less work, work is energy exerted, energy exerted is combustion which uses gas. So the more work required (pertaining to larger tires and more leverage against the motor) the more gas consumed. If your logic worked in the real world, all these hybrid gas efficient cars would be running around on 35" bicycle tires. I hope someone caught what I was saying.

 

Jake, it's good to see you are concerned with gas mileage and take the time to record it. I hope a lot of others do the same. It can't be done once and then say this is what I am getting, it has to be an average over several trips on the same road using the same driving method. I am sure almost everyone is concerned with fuel mileage and the cost of gas now. I wasn't really concerned untill it got to two dollars a gal.

If you are going from a 15" leverage which would be a 30" tire compaired to a 18" leverage which is a 36" tire your only talking abot a 3" difference in leverage and that won't make a lot of difference in the amount of torqe but I'm not going to figure it up, you can if you want. It does take more energy but 99Ranger said they drop the rear end ratio when they put oversize tires on so that would cancel the torque arm effect. It's the same effect as a torque wrench has.

The fact of the matter is you can't increase the size of your tire and not lower the rear end ratio and then expect to take off as fast as before without using more gas.

Quote "If your logic worked in the real world, all these hybrid gas efficient cars would be running around on 35" bicycle tires. I hope someone caught what I was saying." Unquote

You have told what is done thinking it's the wrong thing to do. If you do a search for test cars to get high fuel mileage you will find that they do indeed use large diameter tires and gear the vehicle high. BUT, the tires are narrow like motorcycle tires and very tall and high pressure. It may take the car a 1/4 mile or more to get up to speed and very slowly at that but they do get in excess of 100 mpg. Of course they are only carrying one person and a small engine in a small aerodynamic body. The hybrid cars is an intirely different ball game and can't even be used here for fuel mileage compairason.

I don't own, haven't owned and will not own a vehicle with raised suspension and body and 36" tires. They look nice and I am glad others own them. My stock 2003 3.0L Ranger Edge 4 dr is plenty high for me. It looks nice and is proportionally correct looking at the height it is now.

My truck has a 4.10 rear gear and I get about 18mpg@75mph. If I were to gear it higher to a 3.73 with the same tires at the same speed I figure I would get about 22mpg@75mph just as I was getting on the 93 3.0L Ranger with 3.73 rear end I just sold that was getting 22mpg@75mph and it had almost the same size tires my new Ranger has.

On the other hand if I were to figure up what diameter tire it would take to raise the raito as if I had changed to a 3.73 rear end I would expect to get 22mpg@75mph just as if I HAD changed rear end ratios. I would also expect it to take off slower and accelerate slower and if I tried to take off faster I would lose the gain in fuel mileage I had hoped to get. It's all in how you drive.

The effect is the same wether you change the ratio to the ground by changing the rear end ratio OR the tire size. Either one will increase or should increase your fuel mileage IF and only IF you drive with some sense, that is with your mind instead of your foot.

THE MAIN THING THAT CHANGES WITH A LARGER WIDER TIRE IS THE FOOT PRINT. The foot print or rubber contacting the road is a problem. You can reduce the rolling resistance by using a narrower tire or increasing the air pressure to reduce the foot print of the tire or both. If you run low pressure you can expect to get low fuel mileage and wear the outside of the tires out.

I know I am not going to be able to convince some people because they won't reason it out and just go by what others have told them. The mind ia a hard thing to change and no matter what I say some will never believe it. It's the old saying, "Don't confuse me with facts, my mind is made up".

It really don't bother me if anyone believes me or not but I could not read some of the posts and not tell it like it is. I tried to keep this real world and stay away from the abstract. On the other hand fuel mileage is abstract if someone says, I filled it to 3/4 line and drove x number of miles and filled it up to the 3/4 line with x gals. and it only got 14 mpg. They proved nothing and did not get what they thought.

It has to be filled to the first auto shutoff on a level driveway and drove with fuel mileage in mind and filled again on level driveway to the first auto shutoff. and then computed. The speedo has to be checked for accuracy with a stop watch over 10 or 20 miles at exactly 60 mph on the interstate and corrected if needed. If you don't have everything as perfect as you can get it and drive the same way all the time your wasting your time trying to get fuel mileage or even checking fuel mileage.

Do what you want, believe what you want and drive like you want.

I'll agree to disagree and end it there.

 

Now, I will agree with you on the highway portion, and my mistake: I was thinking practical everyday city driving. Yes people re-gear and get better mileage on the interstate IF they keep their foot out of the gas on hills (granted if anyone did this they would probably slow down to 50 mph on the interstate and **** a lot of people off) but this would not be practical for city driving stop-and-go from light to light unless you get out and push till 20 mph and then jump in and coast.

 

blah...

4.88s on a 4.0, 37x13.50 xcal2 programmer exhaust thats it

city-13-14
highway-14-15

 

GEEZ HighRollerII and I thought I was getting bad fuel mileage.

I don't even check the fuel mileage for city driving cause it can be all over the place because of traffic, stop lights, weather, etc. I would be surprised if I were getting more than 12 to 14 just driving in the city for a full tank of gas.

I don't live in the big city now, The city I live by now only has two traffic lights, about 2000 people and 4 cops.

 

im also rolling on 37" tires and steeper gears..lifted about 9" im happy for what im getting

 

What do you mean by steeper gears? Slang words change from generation to generation.

 

straight and to the point... easy info ^...lol

 

So steeper gears is the same as gearing it lower.

 

hmm..a higher gear..stock is like 4.10 i went with 4.88 which is a higher aka steeper

 

people just end up getting it backwards all the time because the numbers are confusing.
4.88 are a lower gear then 4.10. I do it sometimes to, but i believe that if you have oversize tires on then it would get you better gas mileage=much easier to get the vehicle rolling and less strain on the engine. I think that i have 4.10 on my truck right now what ever is stock, but if I went to 4.56 then I would be able to get the truck going easier and also I would be able to put my truck in 5th gear because right now i can hardly get going good enough to use all my gears. check me if im mislead on this stuff....

 

Ok, my generation called going from a 4.10 to a 4.88 gearing lower or shorter and if you went from a 4.10 to a 3.73 your gearing higher or taller.

When you say steeper it means the ratio numbers are higher which lead me to think you were gearing it higher but I understand now.

greenmonster98, yes, if you change to a 4.88 gear set you will be better off. The truck will take off easier and you may gain some fuel mileage back.

Drivers have been experimenting with tire size and gear ratios since hot rodding started, probably when the first car was made.

 

well that was kinda harsh there