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I was curious as to what everyone with 4.56 gears with a 5spd v-6 on 33's are getting for mpg? I am going to regear to 4.56 soon and am curious what to expect for mpg. With 4.10's v-6 5spd on 33's, when i filled up today, i had 19mpg with the tire size difference figured in.
 

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So you are currently getting 19 mpg w/4:10 gears, and with what tire size?

Thanks.
 

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Ya i got 249.7 miles to the tank. Filled it up full, with 14.2 gallons. Then figured in the .1 difference in mileage because of the bigger tires. so add 24.97 to 249.7 and got around 275 miles to the tank. divided that by 14.2 and got somewhere around 19. Thats around town. I think i get worse gas mileage on the highway. Without the added in tire difference it was around 17mpg.
 

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Isn't the tank size 18.5 gallons? I'm amazed. It must be my tires or something. My truck has been getting really shitty mileage lately and it seems to get worse every tank. I am rarely pushing above 15 now.
 

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I've got a similar inquiry. I have a 99 reg cab 2.7 auto with factory 4.56:1 running on 33x12/16's. I just installed an LCE header and did the rest of the exhaust. Flowmaster, high flow cat.

She sounds great and picked up some top end power, but lost bottom end grunt. So I'm seriously considering 4.88:1's...what will that do to my mpg? And, are my rpms gonna skyrocket on the interstate at about 75, or so?

Also, Digger, how do you like your t-17? How much does it weigh? I'm considering picking one up.

Thanks for all the help
 

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Ya im surprised im getting such good gas mileage, but i try not to have a lead foot. I shift at like 15, 25, 40, 45. It's nice to get such good gas mileage but the little bit off power loss is killing me. Also, the t-17 I like it so far. I-ve only had it for about 2 months. It didnt seem to weight too much. I dont think i even lost any lift with it. Im guessing it wieghs maybe 60-70lbs?
 

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Digger33 said:
Ya i got 249.7 miles to the tank. Filled it up full, with 14.2 gallons. Then figured in the .1 difference in mileage because of the bigger tires. so add 24.97 to 249.7 and got around 275 miles to the tank. divided that by 14.2 and got somewhere around 19. Thats around town. I think i get worse gas mileage on the highway. Without the added in tire difference it was around 17mpg.
I thought 01's had 17 or 18 gallon gas tanks which would mean you were getting closer to 16 mpg's...I could be wrong though. Maybe someone else will chime in who knows for sure.
 

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Yeah, something like 18 gallons. But I think he filled up before he was totally empty -- hence the 14.2 gallons. At least that's what I thought he meant....
 

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Discussion Starter #11
ya i have a 18.5 gallon tank, but i only filled it up with 14.2 gallons, meaning i only used 14.2 gallons also. I always reset one of the mileage counters everytime i fill gas to check gas mileage.
 

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Digger33 said:
I was curious as to what everyone with 4.56 gears with a 5spd v-6 on 33's are getting for mpg? I am going to regear to 4.56 soon and am curious what to expect for mpg. With 4.10's v-6 5spd on 33's, when i filled up today, i had 19mpg with the tire size difference figured in.
Must be my X-terrains - I have the same 4.10's, V6, 285/75R16 manual '01, Xtra cab. I only get 15 if I'm lucky in the winter and 17 in the summer. I was always confused by the whole gear ratio to milage thing. If you put in a larger ratio gear (for your case 4.10 to 4.56) your rpm should be higher at the same ground speed. I understand how you would feel more power but doesn't that mean more fuel consumption? More power, higher rpm's, more gas. How would it improve fuel economy?
 

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Tufemup said:
Must be my X-terrains - I have the same 4.10's, V6, 285/75R16 manual '01, Xtra cab. I only get 15 if I'm lucky in the winter and 17 in the summer. I was always confused by the whole gear ratio to milage thing. If you put in a larger ratio gear (for your case 4.10 to 4.56) your rpm should be higher at the same ground speed. I understand how you would feel more power but doesn't that mean more fuel consumption? More power, higher rpm's, more gas. How would it improve fuel economy?
I noticed more mileage because the engine didn't have to downshift anymore. When I would be on the highway, it would stay in overdrive in cruise control and not have to downshift two gears to get up hills. That helped a lot! Also I found that you usually get up to speed quicker than the 4.10's from stops so I don't have to mash the pedal as hard when accelerating to keep up with traffic. That saved gas too. Having 33" tires with 4.56 gears makes almost the exact same RPMs as having the stock 31" tires with 4.10 gears. Since you have larger tires, it lowers the rpms.

Go to www.ring-pinion.com and use their gear calculator and you will find the RPMs almost match a stock configuration w/ 31's.
 

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Think of it like this.

Your motor has a certain powerband. It was designed for a certain transmission ratio, gear ratio, and tire ratio. When your putting power to bigger tires with your stock set-up, you have to rev your motor more to get the torque needed to move you along. So in effect you will get poor mileage.


Now on the other hand lowering your gear ratio (Increasing the number) will compensate for this, but I am not sure If there is a perfect gear and pinion that would make your truck perform like stock after a set of larger tires. So you will not get stock gas mileage with that.

For example. I have 43ring 10pinion. I have 4:30 gears. I have 31" tires. If I go to a 32 inch tire I will throw off my powerband and I will have to regear to compensate. The next closest gear is 4:56.

4:56 will give me more power and more revs, but it will not bring it to a stock configuration.

If I were to go with 33" tires 4:56 would not be enough to bring it to stock and I would have to go over with a 4:88.


So the moral of this story is that if you get bigger tires no matter what you do fuel consumption will be different, even if it is ever so slight. The question you must ask yourself is. Do I only want to do this job half-way and not re-gear? Or do I want to add bigger tires and make my truck a little peppier in the process.

If your a die hard 4 wheeler you will go with re-gearing with bigger tires. To me the benefits. More power, more clearance is the only way to do it.
 

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The Shocker said:
Think of it like this.

Your motor has a certain powerband. It was designed for a certain transmission ratio, gear ratio, and tire ratio. When your putting power to bigger tires with your stock set-up, you have to rev your motor more to get the torque needed to move you along. So in effect you will get poor mileage.


Now on the other hand lowering your gear ratio (Increasing the number) will compensate for this, but I am not sure If there is a perfect gear and pinion that would make your truck perform like stock after a set of larger tires. So you will not get stock gas mileage with that.

For example. I have 43ring 10pinion. I have 4:30 gears. I have 31" tires. If I go to a 32 inch tire I will throw off my powerband and I will have to regear to compensate. The next closest gear is 4:56.

4:56 will give me more power and more revs, but it will not bring it to a stock configuration.

If I were to go with 33" tires 4:56 would not be enough to bring it to stock and I would have to go over with a 4:88.


So the moral of this story is that if you get bigger tires no matter what you do fuel consumption will be different, even if it is ever so slight. The question you must ask yourself is. Do I only want to do this job half-way and not re-gear? Or do I want to add bigger tires and make my truck a little peppier in the process.

If your a die hard 4 wheeler you will go with re-gearing with bigger tires. To me the benefits. More power, more clearance is the only way to do it.
Ok so if I understand this correctly…

In my case I have a 96 Xtra cab Auto V6, with I believe 4.10s (haven’t verified it yet) and 33 12.50 15s. In order to get back the performance I had stock I need to go to a lower gear ratio \ bigger # for the gears, say 4.88s?

I know that when I made the tire change from 31 10.5 15s to the 33s I lost gas mileage. But what happens to gas mileage when I go to 4.88s? Does it go up with this change? IF so, then how does gas mileage go up if your bringing performance back up? I would think higher performance = lower gas mileage.

Thanks…
 

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I think that the 4.88 would be too much. 4.56 should work well. I found a slight increase in mileage because my engine didn't have to work as hard to push those bigger tires as well as the extra weight I'm carrying around. The gearing did some of the work for it.
 

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It depends on a lot of other things. You will just have to find out. I will say this, if you're all that concerned about gas mileage you're driving the wrong vehicle and doing the wrong mods. Big tires, jacked up trucks and added weight from sliders, bumpers etc. do not equate to the best fuel enonomy.
 
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