I have an '03 with a 6.0 and am about to install a lift kit and 37" tires. I want to regear it so that highway RPMs are the same as stock and give it a little more umph off the line. What are you guys running?
I would not go much lower than 4.10 or 4.30 our 07 6.0 has 8" and 37" tires with 3.73 and it runs good as is.. I think we will go to the 4.30 if we ever do change..
I would go 4.10s maybe 4.30 if you pull and plain to do some wheeling, go Speed Calculator, it will help you pick your gears, your over drive gear is .71.1
Another way to figure is: new tire size divided by old tire size than multiply by current r&p to get new r&p. example 37/31=1.1935483 1.1935483x3.73=4.4519351 So choices would be 4.30 or 4.56. This is all just a sample though. As I'm running 37's with 3.73's and have been for over a year. I don't tow that often and usually nothing over 10k. But after reading posts on here, several run the 4.30's.
Now mpg is a little lower in city, but when driving highway, I usually gain a little. No power mods here.
Honestly,unless you tow real heavy I would stick with the stock 3.73's. Only problem I see is if you add lots of power and have the big tires,the tranny will become the weak point. You would barely notice a change going from 3.73's to 4.10's so I wouldn't even bother. If you had 3.55's then I would regear. I would spend that $1500 or whatever for regearing on a better convertor or something to help out and the money would be better spent.
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