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Discussion Starter #1
OK here's my question what gearing are u running in your truck what tire size and what kind of rpms are u spoolin at 60 MPH?
I'm running 6.5 deaver with 35's running 2k with 4.88's
I'm just trying to get a feel for what gearing to go with. Thinking of 4.10 and 37's only pull Max 12k. Lbs mayby 3 times a year the rest is a daily driver thanks for the info
 

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MINK
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my truck with 3.73s and 33-35s would run 2,000 rpm at what the speedo read to be 70..I cant remember off the top of my head what my boost number where....4.88s and 35s is way overkill..i think your on the right track with 4.10s and 37s
 

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4.10 with 37 is fine. You can use the calculator to figure you exact rpm out with your tranny and rear end gear ratio and tire diameter.
 

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<<< THE GAUGE WHORE...
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I would not go bigger then 4.10's for anything under 37's, and no bigger then 4.30's for anything under 44's...


IMHO...

70 and 2100 with 37's and 4.30's



80 and 2400 with 37's and 4.30's

 

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Really, way is that?

Do you think the stock setup with 3.73 is over geared?

With 38's it would take 4.56 to take it back to stock and that's not accounting for the weight dif. 40s would take even more.

What do you find to be the negatives?

Is it so it gives the these turbos more time to run up thru each gear?

I hear conflicting advise on this by seeming equally experienced persons. I am sure some say it becasue they do not want to lay down the $$ for 2 axles gear changes but that is only some.


I was honestly thinking 4.56 would be correct for the 40's SS-M16 I am planning but had considered 4.30s as I can find either at salvage yard for our axles fairly easily.
 

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<<< THE GAUGE WHORE...
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Really, way is that?

Do you think the stock setup with 3.73 is over geared?

With 38's it would take 4.56 to take it back to stock and that's not accounting for the weight dif. 40s would take even more.

What do you find to be the negatives?

Is it so it gives the these turbos more time to run up thru each gear?

I hear conflicting advise on this by seeming equally experienced persons. I am sure some say it becasue they do not want to lay down the $$ for 2 axles gear changes but that is only some.


I was honestly thinking 4.56 would be correct for the 40's SS-M16 I am planning but had considered 4.30s as I can find either at salvage yard for our axles fairly easily.
Having ran and towed for years with 37's and 3.73's, in every combo you can think of... I miss them.

Yes, it was a bit laggy above 4k, but I never had any EGT issues, no towing issues, better fuel economy, quieter cab and just less wear and tear...

I went with 4.30's because I thought it would make this tire burning differance... nope... Got a smoking deal on them used...now I get worse milage, loud as hell at any speed above 65 and its just more wear and tear...

Again, this is just my opinion after about 950k running these trucks with stock, modded, and otherwise turbos, injectors, tire sizes...
 

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So running 37's with stock gearing works good eh.
If i have a levling kit and some minor trimming can i fit that size for a bit of offroading i dont want a huge lifted truck. would like a 16x10 with some backspacing work?

Oh. its a 2000 f250 psd.
 

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MINK
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37s will take more than minor trimming on a stock truck especially with a 10" wide wheel....id run a 4"lift with a narrow 37 like a 12.50
 

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what about with bushwacker cut out flares
 

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With those cut outs you can run 38" stock and 41" with a 4.5" lift. I am planning 40x14.5x20 on 20x12 with cut outs and a 4.5 " lift.
 

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<- Sums it up
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35's with stock gears. I tow heavy and tow in Direct. No EGT problems at all and still 18mpg on the freeway solo.
 

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<-- it's like that
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I'm running 4.30's with 36" tires. Personally I love the combo for both highway driving as well as towing.
 

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I have 4.30's and 35's. It will tow like not other. However if I were to do it again, I would stick with the 3.73's. Mileage is horrible if u go faster than 55mph! I'm headed down state today, so I can give u mpg on a long distance trip on the expressway.
 

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Discussion Starter #15
Thanks for the replies. Some MPG #'s would be great I'm only 13 MPG around town I think 4.10's 37's and a chip should easily take that # up. What is the largest tire that u guys have stuck under a 6.5 without modification to the fenders? Thanks again
 

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Thanks for the replies. Some MPG #'s would be great I'm only 13 MPG around town I think 4.10's 37's and a chip should easily take that # up.
I'm about 2000 RPM's at 67 mph. In the summer I usually average around 16 mpg mix city/highway. I have hit 18 mpg on the highway before, but that was staying at 65 mph or less the entire time, and being very very very gentle on the go pedal. On a recent trip to Houston and back, I was towing a cargo trailer. On the way down I didn't have much in the trailer that I cared about, so I drove 80 mph+ averaging 12-13 mpg. On the way back the trailer was loaded down, and had some stuff that would easily break, so average speed was 60-70 mph, and I got 14+ mpg's. Not too bad with a trailer in tow.
 

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Really, way is that?

Do you think the stock setup with 3.73 is over geared?

With 38's it would take 4.56 to take it back to stock and that's not accounting for the weight dif. 40s would take even more.

What do you find to be the negatives?

Is it so it gives the these turbos more time to run up thru each gear?

I hear conflicting advise on this by seeming equally experienced persons. I am sure some say it becasue they do not want to lay down the $$ for 2 axles gear changes but that is only some.


I was honestly thinking 4.56 would be correct for the 40's SS-M16 I am planning but had considered 4.30s as I can find either at salvage yard for our axles fairly easily.
I think it is more of a personal preference. Since I don't tow much and spend 90% of the time on the highway, I prefer to get better mileage. So lower RPM's on the highway is good for me. I wanted to be in the 18-1900 or so range at 70 mph, and I am right there. If I want to tow, or I want to hammer on it... I just take it out of OD and I am gone... LOL

 

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Got 13.5 mpg on the way down at 75 mph. However it felt alot faster than that. I have to fill it up for on the way back. Traffic was horrible and had to sit in a traffic jam for 1 1/2 hrs yesterday on 127. But on the way back I drove 70 mph, but all the stop and go and 1 1/2 hr sit killed me. Rpm's at 60 are just shy of 2000.
 
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