The Gear Thread
09-29-2011, 12:14 AM
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The Gear Thread
Ok so i dont really understand the relationship between tire size, gear ratio, and gas mileage. I am running 30s and getting average gas mileage i am considering 33's down the road. and i will DEFINITLY need new gears to be able to afford the gas on 33s. But if i go ahead and switch out my gears while i have the 30's would i get awesome gas mileage? Idk i need a rearend tutorial.
09-29-2011, 01:25 AM
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I am unable to read that chart?
I would wait, regear with the tires and run 4.56's. also leaves the door open for 35's later. I loved 4.56 with 33's.
The tire that is small will spin faster then a larger tire at the same speed due to the diamiter of the tire. the same distance is traveled. but the larger tire does not need to spin the same amount as the smaller tire to achieve the same distance. so if you want to keep the engine in its optimal running range you will need to change the gear(diff) ratio to compinsate for the tire change. this will allow you to have the same rpm with a 29" tire as a 44" tire. hope that helped explane it...
Other factors are wind drag, weight of the bigger tire, loaded with gear for camping, 4wheeling ect, all of which will rob power and make hills and other loaded situations will take power. gearing will also help compensate for these situations buy having you higher in the power band and make the power you already have more usable... good luck. gears can confuse people real fast. if you wan to learn how a diff really work in simple terms watch this
I would wait, regear with the tires and run 4.56's. also leaves the door open for 35's later. I loved 4.56 with 33's.
The tire that is small will spin faster then a larger tire at the same speed due to the diamiter of the tire. the same distance is traveled. but the larger tire does not need to spin the same amount as the smaller tire to achieve the same distance. so if you want to keep the engine in its optimal running range you will need to change the gear(diff) ratio to compinsate for the tire change. this will allow you to have the same rpm with a 29" tire as a 44" tire. hope that helped explane it...
Other factors are wind drag, weight of the bigger tire, loaded with gear for camping, 4wheeling ect, all of which will rob power and make hills and other loaded situations will take power. gearing will also help compensate for these situations buy having you higher in the power band and make the power you already have more usable... good luck. gears can confuse people real fast. if you wan to learn how a diff really work in simple terms watch this
Last edited by Gorillaxj; 09-29-2011 at 01:33 AM.
09-29-2011, 01:26 AM
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ok what are the numbers in the chart? rpms? and also if i had 4.56s with 30s what would happen to my mileage? if im not mistaken it would make me take off faster and have higher rpms at highway speed. correct?
Last edited by toogreat; 09-29-2011 at 01:28 AM.
09-29-2011, 01:39 AM
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yes they are rpms, based on a trans in over drive (4th in auto, 5th in manual) its slightly flawed due to guessing your trans ratio... but close enough. and this chart is based on rpm at 60mph.
4.56's are to low for 30" tires. 4.11's are ok, but for the money I would get as much as you can out of the $$ spent. 4.11's aren't worth the money IMO... its just not a big enough change from 3.55's, 3.07's to justify while running 33's.
you didn't list manual or auto in you "spect" or thread. that may help but if your going to 33's and regearing I would go 4.56's either way. (with 33's)
4.56's are to low for 30" tires. 4.11's are ok, but for the money I would get as much as you can out of the $$ spent. 4.11's aren't worth the money IMO... its just not a big enough change from 3.55's, 3.07's to justify while running 33's.
you didn't list manual or auto in you "spect" or thread. that may help but if your going to 33's and regearing I would go 4.56's either way. (with 33's)
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09-29-2011, 02:00 AM
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If you have a manual you have 3.07's (most likely)
if you have an auto you have 3.55's (most likely)
3.31's are in the middle and would not make a noticable difference either way.
if you stay at 30" tires keep what you all ready have. if you upgrade to 33's, I would recomend 4.56's at that time.
Last edited by Gorillaxj; 09-29-2011 at 02:08 AM.
09-29-2011, 12:17 PM
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yes they are rpms, based on a trans in over drive (4th in auto, 5th in manual) its slightly flawed due to guessing your trans ratio... but close enough. and this chart is based on rpm at 60mph.
4.56's are to low for 30" tires. 4.11's are ok, but for the money I would get as much as you can out of the $$ spent. 4.11's aren't worth the money IMO... its just not a big enough change from 3.55's, 3.07's to justify while running 33's.
you didn't list manual or auto in you "spect" or thread. that may help but if your going to 33's and regearing I would go 4.56's either way. (with 33's)
4.56's are to low for 30" tires. 4.11's are ok, but for the money I would get as much as you can out of the $$ spent. 4.11's aren't worth the money IMO... its just not a big enough change from 3.55's, 3.07's to justify while running 33's.
you didn't list manual or auto in you "spect" or thread. that may help but if your going to 33's and regearing I would go 4.56's either way. (with 33's)
[yes they are rpms, based on a trans in over drive (4th in auto, 5th in manual)]
The chart is not based on overdrive it is based on a 1 to 1 gear ratio, third gear in an auto and fourth gear in a manual.
65x4.88x336x.79/35 = 2405.6 rpms
If you want to use the chart just multiply the charts numbers by your overdrive ratio. Auto= .75 Manual= .79
09-29-2011, 12:53 PM
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I am unable to read that chart?
I would wait, regear with the tires and run 4.56's. also leaves the door open for 35's later. I loved 4.56 with 33's.
The tire that is small will spin faster then a larger tire at the same speed due to the diamiter of the tire. the same distance is traveled. but the larger tire does not need to spin the same amount as the smaller tire to achieve the same distance. so if you want to keep the engine in its optimal running range you will need to change the gear(diff) ratio to compinsate for the tire change. this will allow you to have the same rpm with a 29" tire as a 44" tire. hope that helped explane it...
Other factors are wind drag, weight of the bigger tire, loaded with gear for camping, 4wheeling ect, all of which will rob power and make hills and other loaded situations will take power. gearing will also help compensate for these situations buy having you higher in the power band and make the power you already have more usable... good luck. gears can confuse people real fast. if you wan to learn how a diff really work in simple terms watch this How does the differential work? Aroundth1937 - YouTube
I would wait, regear with the tires and run 4.56's. also leaves the door open for 35's later. I loved 4.56 with 33's.
The tire that is small will spin faster then a larger tire at the same speed due to the diamiter of the tire. the same distance is traveled. but the larger tire does not need to spin the same amount as the smaller tire to achieve the same distance. so if you want to keep the engine in its optimal running range you will need to change the gear(diff) ratio to compinsate for the tire change. this will allow you to have the same rpm with a 29" tire as a 44" tire. hope that helped explane it...
Other factors are wind drag, weight of the bigger tire, loaded with gear for camping, 4wheeling ect, all of which will rob power and make hills and other loaded situations will take power. gearing will also help compensate for these situations buy having you higher in the power band and make the power you already have more usable... good luck. gears can confuse people real fast. if you wan to learn how a diff really work in simple terms watch this
How does the differential work? Aroundth1937 - YouTubeA larger wheel will get more distance than a smaller wheel. That is why your speedometer will not show actual miles with bigger tires, because they have traveled farther.
Two different size wheels will travel the same distance only when on the same axle, but side by side testing will show the larger wheel goes farther.
Try this for fun, get your stock wheels and your larger wheels and put them next to eacother and make one line on the side of the tire touching the ground, then rotate them both until the line is back touching the ground, you will see the larger wheel travels farther.
Last edited by BigBear; 09-29-2011 at 12:56 PM.
09-29-2011, 01:07 PM
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Bigbear, you can also go to the Tire Rack webpage and check the specs for a tire and it will give you the revolutions per mile.
That way you can find out the actual difference in distance per revolutions between actual tires.
That way you can find out the actual difference in distance per revolutions between actual tires.
09-29-2011, 01:47 PM
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I was reading the thread and noticed a small error.
[yes they are rpms, based on a trans in over drive (4th in auto, 5th in manual)]
The chart is not based on overdrive it is based on a 1 to 1 gear ratio, third gear in an auto and fourth gear in a manual.
65x4.88x336x.79/35 = 2405.6 rpms
If you want to use the chart just multiply the charts numbers by your overdrive ratio. Auto= .75 Manual= .79
[yes they are rpms, based on a trans in over drive (4th in auto, 5th in manual)]
The chart is not based on overdrive it is based on a 1 to 1 gear ratio, third gear in an auto and fourth gear in a manual.
65x4.88x336x.79/35 = 2405.6 rpms
If you want to use the chart just multiply the charts numbers by your overdrive ratio. Auto= .75 Manual= .79
A larger wheel will get more distance than a smaller wheel. That is why your speedometer will not show actual miles with bigger tires, because they have traveled farther.
Two different size wheels will travel the same distance only when on the same axle, but side by side testing will show the larger wheel goes farther.
Try this for fun, get your stock wheels and your larger wheels and put them next to eacother and make one line on the side of the tire touching the ground, then rotate them both until the line is back touching the ground, you will see the larger wheel travels farther.
Two different size wheels will travel the same distance only when on the same axle, but side by side testing will show the larger wheel goes farther.
Try this for fun, get your stock wheels and your larger wheels and put them next to eacother and make one line on the side of the tire touching the ground, then rotate them both until the line is back touching the ground, you will see the larger wheel travels farther.
09-29-2011, 01:50 PM
#15
