I've been thinking about this for a while and hesitate posting cause I'm sure most people will hate the idea. I'd love a 4.10 rear end for towing but there is no way I'm spending the money to get installed or have to suffer with the poor gas mileage when not towing. I only tow long distances about 3-4 times per year.

I was thinking instead of going to a taller dif what if I lowered the overall diameter of the tires. To go from a 3.55:1 rear end to a 4.10 is a .866% difference. My stock tires are 30.6", so I would need a tire with 26.5" OD to be equivalent.

I will need a tire that has at least the 2271 max load rating (same as the stock tires), need to determine the smallest rims that will fit the truck (I know 17" will fit, not sure about 16"). Not positive yet that combination of tires exists, a quick call to Tirerack will tell me. Also, will need to do 5 wheels/tires as the spare would be way to large especially if towing. I would do 5x$50 cheap rims and 5X$100 tires. Lets say $800 once balanced (very cheap here in Dallas).

Now I'm out ~$800 and I will have to change them out before/after tow trips. BUT the truck keeps the good looking rims that are on it and I don't have to kill my mpg the rest of the year with a 4.10 in back.

More day dreaming than anything else at this point as I haven’t even bought the bigger trailer yet but something to think about. Thoughts, am I crazy?

 

You also have to think about how you are going to recalibrate the speedo/odo.

 

Why do you think 4;10 will kill your MPG???

 

How about a Gear Vendors overdrive unit?

 

My fuel mileage went UP 2-3 mpg's with a swap to 4.10 gears...and my truck doesn't look rediculous from switching to a 26" tire

Are you also talking about being "out" $800 for the smaller tires??? Gears in the rear axle, parts & labor, should run you close to $600.

 

If you have a 2wd truck, a 4.10 gear is cheaper and safer than the smalelr tires. You won't find any tires that small with 2250# load rating. And 4.10 won't kill your mileage, even with stock tires. I bet ther is no effect on mpg.

 

I don't think that 13.4% difference in gear ratio is going to really affect your gas mileage that much. You're talking about a difference of a couple of hundred RPM, which shouldn't kill your mileage.

Anyone else notice much difference in fuel mileage with 4.10s?

 

I went from 3:55 to 4:10 in my 04 SCrew. Though rpm's are a bit higher, which is one of the intents, I haven't really noticed a change in gas milage. What I immediately noticed was these gears are great for towing and all around driving has more spunk. I use an Edge for recalibration. The gears were these best investment I've made.

 

I'm surprised a couple of you have seen no loss or increased fuel mileage. I know I know, the amount of fuel isn't directly related to the rpms, but I still thought 2300 prms vs 2000 (as an example) would use more fuel. I guess I need to kill this concept in my mind.

I hate the idea of running silly little tires, especially when I show up at a track with an otherwise badass looking truck and nice trailer. I'll wait until I actually get the enlcosed trailer to do anything and if it is really lugging to pull her I'll just change out the rear end.

Oh ya, that Gear Vendors Overdrive thing is pretty wild. Way more than I want to do on a warrantied truck though. Plus I don't know how Xcal2 would sinc up, or if it would. Pretty cool in concept for sure though.

 

The reason people often see improved mileage is due to power bands and aerodynamics. You are pushing a brick into a tornado - if you have more power with less throttle, mileage goes up. There is, of course, a point where you pass the power needs and are spinning the engine too fast for it to be efficient.

 

Hey... don't steal my sloagan about the F150... as being a "Flyin' Brick"...

When I take my "Flyin Brick" out on the road, it not only hogs gallons of gas, but it tows everything in sight.

On the lighter side of things... 4.10's will help you out in many more ways than 1. Just don't look silly and go with tiny tires.

 

Where is a picture of paul's (fasterf150) with his 16s and 55 series tires :o




And he has figured his effective gear ratio to be close to 3.90s i believe, so you would have to go even smaller to get to 4.10s
-Patrick

 

Next thing to do is to put Geo Metro rims and wheels on...

Those babys are like what 14" rims and tires? Or are they 13" on a Metro?

A friend of mine has one... I should go look...

 

Throw a set of Ford Festiva wheels on it - those are 12".

 

Engine RPM is a very very small piece of the puzzle. Engine load is much bigger. Before the gear change yes, my rpm's were several hundred lower but the gas pedal was half way to the floor to hold a speed. (that's an exaggeration...but you get the point) If you so much as moved the gas pedal to pass or accelerate, the converter would either unlock or she'd downshift. Now, I can accelerate pretty much normally from as low as 40 mph IN O/D with no problems. I use probably 1/2 the gas pedal I used to use to accomplish a given task. That's your gas mileag and that's where you're getting wrapped up in the wrong idea. My 2-3 mpg increas is half and half city/freeway driving. I'd like to run out a full tank on the freeway...I bet I'd see a 5 mpg increase based on what I've seen so far!