[JustRammit]

I am looking for the correct gear ratio for my new ( to me ) Ram. It has a 6" lift installed and 37" tires. It's a 2007 4x4 SLT quad cab 5.7...

I do mostly city driving but will be doing more highway as I am thinking about purchasing a mid-sized travel trailer that I will tow occasionally. Off road only a few times per year during hunting season, and some deeper snow driving in the winter.

I would like to find the happy medium between better low end pull, and fuel economy, Any thoughts?

 

[RamBiker11]

With 37's you're going to want to go with at least a 3.92 and maybe even a 4.10

 

[TheSatinPumpkin]

4x4 QC with 37" meats in its self is a heavy barge so i would go with 4.56's esp' if the majority of your driving is city.

 

[brandonjansen]

4.56's will definitely be better in the city power wise, same goes for pulling a travel trailer. 4.10's would do the job and give you slightly better fuel economy. It all depends on where you want your RPM to be in each gear at certain speeds. That's how I'd determine what to go with.

 

[JustRammit]

Thanks guys. I stopped in at a performance shop yesterday.... The owner had a new gen Chev 4X4 6" lift with 35's. Told me he's running 488's and gets 2100 RPM at 60 MPH, Is this possible? He told me 488 range was perfect for mine but seems like way too much HWY RPM for me.

Would it be possible for someone to advise me with 456 gears what the 60 MPH RPM would be? Thanks in advance.

 

[TheSatinPumpkin]

depends on the trans/gearing. You wont be able to do 4.88's as a bolt on though (unless you never engage 4x4).

 

[JustRammit]

Thanks... Trans is bone stock no tuning.

 

[TheSatinPumpkin]

with our 545re trans w/ 35's and 4.88's your rpm in OD would be 1883

I ran 4.88's for 2 years and w/ 28" tires my RPM @ 70mph in OD was 2700rpm.

 

[JustRammit]

Great thank you I have 37's so RPM would be?

 

[TheSatinPumpkin]

Going 70mph w/ 4.56's and 37" tires your OD will be around 1940rpm

 

[TheSatinPumpkin]

Use this to get an idea on your RPM per tire size.

mph x gear ratio x 336
__________________ x gear ratio trans
Tire diameter

gear ratio trans = .67

 

[JustRammit]

That's not bad! Its a pretty happy medium for my needs.

 

[cvieke]

I have an 08 with 4.56 gear and running 35" tires. At 60 mph I'm turning about 2050 rpms

 

[Bigboc]

Cvieke what's your fuel Eco look like?