I'm looking at a new ram... What are the benefits of some rear axle ratio over others?

The one I'm looking at has the upcharge for a 3.92 axle ratio.

My understanding is the 3.92 is going to get crappier gas mileage. Is the added peppiness worth it?

I have a new spare set of 33s though, does that mean I can pretty much throw the 33s on there and have it drive more like a 3.55 with stock diameters?

I never haul more than 4k lbs (maybe 10 miles every year?), and normally I only haul a motorcycle. am I really going to regret the 3.92?

Looking for a 3.7l 4x2 w/lsd/ASD for DD truck. I have a 5.9 magnum I'm going to keep for beating up.

 

Numerically higher ratio's(3:92-4:56) on the v8's actually net you better gas mileage than the numerically lower(3:55's) because the lower geared ratio's lug the motor and keep it out of it's "sweet spot"

I'm not to familiar with the gearing on the v6 though, but if you do towing, I would opt for the 3:92's.
If you do put larger diameter tires on your truck, yes, it will lower the gear ratio numerically(i.e from 3;92 down to 3:70ish) but then you will be rotating a larger mass which does put a little more strain on your trans and prob would hurt gas consumption slightly. Using the tires to reduce your overall gear ratio isn't the same as changing the gears.

 

Thanks, I appreciate it!

 

I doubt the higher numerical ratio will get better mileage,it may not hurt very much,if it got better mileage there would be no need for the lower numerical ratio's.

 

Actually dirtydog is correct, especially when you are talking about a truck with a transmission that essentially has two over-drive gears. The only situation where numerically lower gears will see a mpg increase is on the open highway, at relatively high speed, when not hauling/towing and the terrain is fairly flat. In all other instances numerically higher gearing (to a point) will net better MPG gains.

In talking with engineers on this issue and questioning the fact that Dodge (as well as most truck manufacturers) are trending toward numerically lower gearing is more for emissions than anything else. Lower RPMs at a given rate of speed produces less emissions. Also they can give the vehicle a better MPG rating since there are no real testing standards and can use the best possible (but not real world) scenarios where the lower gears can give slightly better MPG results. But in a real world, numerically higher gearing means you have to use less throttle to attain the same RPMs that you would have to with numerically lower gearing, less throttle = less gas used. Numerically higher gearing gives much better power AND fuel economy when accelerating as opposed to cruising, so in city type driving conditions, higher gearing usually gives a good bump in fuel economy.

I find that in a V8 truck, especially a heavier (QC and/or 4x4) with the 545rfe transmission that the optimal balance of power and fuel economy is to try to attain an "effective gear ratio" of between 3.9 and 4.1 to 1. Does this mean that 3.92s are ideal for you? Maybe, maybe not. Effective Gear Ratio factors in tire size into the equation as straying away from the factory tire size (and the size where the gear ratio is based) will effect the ratio greatly whether going to larger or smaller size tires.
For example, I run 4.56 gears, but my tires measure 34.8", so my Effective Gear Ratio falls right in at about 4.1:1...

 

I'd also at least get the 4.7 v8. Not the v6