hey guys im new to the site, needing yalls opinions on which gear to choose for my truck, looked everywhere on here and nothing that really helps so here it goes. got a 04 ram 1500 with the hemi, 5 inch lift and 325x60x18 mickeys. i know my stock gears are 3.55 needing something that will help my mpg now around town i get bout 10.5 and interstate bout 12. i drive bout 60/40 city/interstate in general i can noticeable tell the motor and tranny is doing almost all the work needing something to take the strain off them and possible mileage gains. thanks!

 

You can pretty much forget about gas mileage gains with the lift and larger tires. Re-gearing will help (prolly about 2 mpg) in town, but you'll give it right back on the highway.

As for the power, the tires in combination with the paltry 3.55 gears now have you down to an effective gear ratio of about 3.44 : 1. For the best performance/fuel economy, you ideally want this ratio between 3.9 - 4.1.

So, in your case, a change to 4.10 gears will give you an effective ratio of about 3.97 : 1, which is about perfect. If you ever plan on going to larger tires than the roughly 33.5" diameter ones you have now, then I'd go to 4.56s.

However, re-gearing is expensive and I'd expect you'd pay in the $1500 range for gears, install kit and labor. It would take you years to make that back in fuel savings, although the re-gearing will take a LOT of strain off your transmission.

 

if i go with the 4.10 what kind of rpm would i expect at highway speeds. how will this help me as far as my tranny searching for gears on the littlest hill at 70-75 would it pull better

 

I see about 2150 rpm at 70 mph with 35" tires and 4.56 gears, I'm guessing 4.10s with 33.5s would be in that ballpark, maybe a tad lower.

Yes, the higher RPMs will both get you up into the power bandwidth faster and keep you there better, making it unnecessary for the transmission to "search" for gearing nearly as much as it does now.

I am by no means trying to talk you out of a gear swap, your truck will feel as though it has a lot more power, BUT at the same time, I don't want you disillusioned into thinking you are going to see big MPG changes. You'll gain in town because your engine gets up into the HP and Torque curve sooner with less throttle, but because you'll be taching a bit higher at highway speeds, you'll lose a smidge or stay where you are now at best...

 

thanks for the advice hammerz71, very appriciative

 

Pretty much every guy on here who has re-geared will not have anything bad to say about it. They all love it as do I in mine

 

ive done more searches today and now im torn between a 4.10 and 4.56, really need some help with this im new to re-gearing. the only thing that i tow is a toy trailor with 2 atvs and boat occasionally, i really dont want to put that kind of money in the gears and regret it, i understand that mpg wont change much if any just wanting to take the strain off tranny and motor would rather do gears right the first time rather than 3 grand or more on a tranny

 

with the 545rfe that essentially has two overdrive gears, you'd be fine with 4.56s with any tires over 33". The only way I'd do the 4.10s is if I planned to always stay at 33'ish tires AND I did a LOT of interstate driving...

 

if i was to go with a 4.10 my actual ratio would be around 3.86? and with a 4.56 it would be around 4.27? with my 33.5 tires i live in hilly east tennessee which would benefit me more

 

ok so me and my wife took a pretty good ride down the interstate today and with my 3.55 and 33s i took my rpms at certain speed wanted to see what you guys think. at 70 it ran at 1700 rpm at 75 1800rpm but what really concerns me is the 1450 at 60 these are my normal driving speeds noticed even at 75 the motor and tranny still had trouble with all this stated what do you guys think i need gear wise?