Rear End recommendation ~ Towing 37' Toyhauler on 35" Tires

[unmtv8d]

I currently have a 2006 with the LBZ motor lifted on 35"s... I tow a 37' Fifth Wheel Toy Hauler and was thinking about re-gearing my truck which currently has the 3.73. Some are saying just put a 4.10 and others are suggesting up to a 4.56... Has anybody had or know similar situations and what may work best? Upsides and downsides?

 

[coker6303]

Calculate it out. You can figure up what your rpm will be at cruising 70. I'm betting 4.56 but math will show you where you need to be

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[darkness]

35's and 4.10's are super close to stock gearing/tires. its what i run. heres a calc for you... www.f-body.org/gears

 

[coker6303]

with 37's, this chart is comparing your 3.73 to 4.56 gears (looks to me like 4.56 is going to be perfect!). 4.56 gears and 37 in tires put you very close (within 50rpms) to the same cruising rpm at 70 as stock tires and 3.73.

you can find the calculator on grimmjeeper.com

 

[darkness]

he's running 35's...pulling a 37' trailer

 

[coker6303]

he's running 35's...pulling a 37' trailer

oops, i'm moving slow! it's monday.

35's and 4:10's are within 40rpm's of stock at 70 mph.

You would be hitting 1900 rpms cruising with 35's and 4:56 gears in 6th at 70. if you're not worried about mileage, this will definitely be stout!!

 

[jlawles2]

When I run the numbers, I get a 200 rpm difference with 4.10 and a 20 rpm difference with 4.56 gears.

 

[D-MAX Mafia]

I run 4.56's, makes for a good street setup with the heavier wheels/tires. I have towed a few trailers 10-15k lbs and the lower gears make running hills pretty easy at high speed.

On the DroidX

 

[coker6303]

When I run the numbers, I get a 200 rpm difference with 4.10 and a 20 rpm difference with 4.56 gears.

I used 31" tires for stock

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[jlawles2]

I used 30.47" (245 75 R16)for tire diameter and had 2160 rpm @ 70 mph.
Circumference of Stock tire is calc'd at 95.72" while the 35's have a circumference of 109.97"

 

[radvans]

I type a 40' w/4.10 and its perfect. No problem with power and didn't change mileage. Had like this for over 100,000.

 

[crazycrew]

My neighbor has 4.10 with his 35's and absolutely loves it. He said its exactly like when he drove home from the dealer


Sent from Mac Daddy Land

 

[bartman432]

I'm running a 4:10. This is what the gear intaller recommended with a 35" tall tire. I tow a 31' 5th wheel and it's perfect.

 

[Colt]

Are you changing the whole rear end? Dana 80 out of older Dodge ton up is priced real good with posi or what you want. That engine should run fine at 2K rpm don't you think?