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Discussion Starter #1
I'm considering going ahead with a gear change on my truck. It currently has 3.73 gears and simply needs more bottom end. My current tires are 31.6" diameter (265/75-16). My next tires will be 32.8" (285/75-16 or 305/70-16). Of course this will exaggerate an already existing problem. With that in mind, should I go with 4.10 or 4.56 gears? I'm performance oriented but don't want to forget about mileage. What kind of RPMs will I turn and how bad will it impact my mileage, one vs the other? Check my sig for my setup.
 

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Mayhem, Like Me
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you should be good with 4.10's... if we had a better OD ratio I'd say the .56's for sure... I still get 20+ out of mine on the hwy with the converter locked.... even with my short ass tires and cam etc etc...
 

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Discussion Starter #3
Is there are chart anywhere that shows RPMs with a given tire and gear combo using Over Drive? I'm just afraid I won't tell much difference going from 3.73 to 4.10. But then again, I don't want to gear too low either.
 

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Mayhem, Like Me
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I found a good one a while back... let me see if I can dig it up.
 

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HAWK just regeared to 4.56's with 315/70-17's and said he though it was a little too low for that size tire. Makes me want to go with 4.10's when I regear (5.3, 315/70-17's)...but I'll be doing 4.56's and dealing with the gas burning on the interstate.
 

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Discussion Starter #6
He thought 4.56 was too low geared for nearly a 34.3" tire? That's surprising!
 

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Discussion Starter #9
I found a calculator and figured the following. I wanted to know the RPMs at 70MPH cruising the highway. I took into account that my tranny has a .70 OD. On the left is the tire diameter. I won't be going to the larger tires right away.

________3.73__4.10__4.56
31.65___1940__2135__2375
32.8____1875__2060__2290
 

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Mayhem, Like Me
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those are liveable RPM's... go with the .56's IMO... thats about how my 4.10's are with my short ass tires.
 

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Discussion Starter #11
Hang on. I'm going to edit the above to show what the RPMs are with my 3.73 to see the net change.

________3.73__4.10__4.56
31.65___1940__2135__2375
32.8____1875__2060__2290
 

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Discussion Starter #12
I'm a little worried what my mileage would be running 2300-2400 RPMs @ 70MPH on the interstate. How much worse would that be than 2100 RPMs. I'm currently only running about 1900. Where's the balance here? The best bang for the buck?
 

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Discussion Starter #13
How about Richmond Sportsman gears? I can get both sets of gears and basic install kits delivered for $484. That does not include bearings. My truck only has 50K on it.
 

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Mayhem, Like Me
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I'm a little worried what my mileage would be running 2300-2400 RPMs @ 70MPH on the interstate. How much worse would that be than 2100 RPMs. I'm currently only running about 1900. Where's the balance here? The best bang for the buck?
shouldnt affect it too much... you ever considered 4.30's??? good noticeable jump from the 3.73's but not quite as deep as the .56's... but a hair more than 4.10's
 

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Discussion Starter #15
I just did a little research and don't see 4.30s as an option for my truck. So you don't think my mileage will drop too much between 4.10s and 4.56s? If I get it right, I might even get better mileage in town. This heavy pig will accellerate easier.
 

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Mayhem, Like Me
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they make 4.30's for the 8.6 10 bolt... I am 100% sure they do... get with Yukon Gear. I think they will have them.
 

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Discussion Starter #17
I'll also need a set for the front.
 

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I thought Motive carried the 4.30 gears? I could be completely wrong though
 

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No shit...I can get 4.30's? I would think that'd be a great gear for small 35's....no?

EDIT: Sorry to whore up the thread...
 
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