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Discussion Starter #1
Like the title says. Who is running 40" tires and what gears are you running.



I have read about most guys running 4.56's... but recently heard 4.30's are better??? What RPM are you at going 60 and 70 mph? I have a chart but some guys are not matching up to that.



Thanks!
 

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I've still got the stock 3:73 gears and have been told to leave them from the local 4x4 shop. they have a shop truck with 41" iroks that hauls there rock buggies and he said they did the 4:56 gear swap and went back to 3:73 because it was a turd. I personnally love the tach stayin under 2 grand runnin 80mph. I accidently hit 115 on the GPS last week comin back from Memphis, TN and it was still ridin like a dream.
 

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Discussion Starter #3
So what RPM are you at going 70?

Lets see some pics too!
 

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I had 39.5" TSL's on my old truck a 99 F250 powerstroke with 11"s of lift. I installed 4.88's and it was a little too much. It worked very well for stop and go but too many rpms down the highway. I would say 4.30's if you do alot of highway or 4.56's if its mixed driving.
 

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All depends on what you are going to use the truck for. If you are going to use it like a truck ( for towing ) you want 4:56, 4:30's will lower rpm's for highway driving, but leaving it stock would suck for towing!! Just my .02.

NCH
 

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Discussion Starter #7
I had 39.5" TSL's on my old truck a 99 F250 powerstroke with 11"s of lift. I installed 4.88's and it was a little too much. It worked very well for stop and go but too many rpms down the highway. I would say 4.30's if you do alot of highway or 4.56's if its mixed driving.
Good info

All depends on what you are going to use the truck for. If you are going to use it like a truck ( for towing ) you want 4:56, 4:30's will lower rpm's for highway driving, but leaving it stock would suck for towing!! Just my .02.

NCH
Definitely not leaving it stock :hehe: I drive a lot of highway miles. Kinda leaning towards the 4.30's ...

Anybody else running 40's??
 

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Do what you want, but I towed a 95 1ton chevy deisel dually 300 miles on an 18 ft metal floor car hauler and never felt it behind me. That's as much as I'll ever tow. And to answer the 70mph? I run 1650 at 70 and get 13mpg on the road. I don't use my truck to tow, if I did I would have never lifted 12" with 40s.
 
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