Seems there aren't very many options available.
I went to 365/75-16s and would like to install at least 3.73:1 to get some of my around town acceleration and milage back.
Am I lookin' in all the wrong places?
runnin' 3.55:1 now>>>>edit - runnin' 3.73:1<<<<

Rusty

 

In all honesty with the 5.4 you might want to look at lower gears than a 3.73, which is stock. 3.55 is higher than stock.

 

Aftermarket gears might be labeled as being 10.25". There's a full range of options: 3.55, 3.73, 4.10, 4.33, 4.56, 4.88, 5.13, and 5.38.

1999-2008 Super Duty/excursion - 10.5" Rear Axle - 10.5" Gears

4.10s and 4.30s seem to be popular with the modular guys, even with stock sized tires.

 

There is plenty of gears out there. I am about to replace my 3.73 with a 3.55 myself. Randy's Ring & Pinion has a good assortment also. I am using a OE Ford gear myself.

 

Yea, my mistake I thought I had 3.55s really got 3.73s, that screwed up the calculator

I noticed alot of 10.25s, I always thought that was a different axle?

I used to go to Jeff's when he worked outta his barn, my doberman chased the horses.

Looks like 4.11s 'll get me close to the stock ratio.

4Lo.com :: Tire Size Change, New Gear Ratio Calculator

Thanks fellas

Rusty

 

Go to 4.30s.

 

I second the 4.30's!! I am currently getting my 3.73's swapped out for 4.30 gears. My brother has an 08' on 17" rims with 31" tires and his 4.10 gears feel great! Plenty of power and pick up plus better mileage. My 08' is an FX4 rolling the factory 18" rims with 33" tires and it is a sloth!! I did the calculations as well and 4.30 gears will get me right at the same rpm as my brothers! Should have close to the same power minus the loss for turning the extra weight of the bigger wheels.

 

Go with 4.30. If u have an automatic trans, you may want to go a little more. You won't regret it.

 

I second the 4.30s. Did that after I put 35's on my Excursion, it took the V10 out of it's power band for towing with the stock 3.73 gearset. Now i've got all the power I need... well at least I thought I did until I bought the 07 F350 with the diesel engine . Now it does all my towing, still though no regrets in going with the 4.30's, it made all the difference.

Happy Motoring.
-Mark

 

installed 4.30 with stock tires on my 5.4, wouldnt waste the money on 4.10 gears

 

365/75-16's?
Those would be close to 37" tall. And heavy.
So you have two whammies affecting performance: The effective gear ratio change AND the dramatic increase in rotatina mass and inertia.

If you want to get back anywhere near stock acceleration, you will have to go REALLY deep. Like tothe 4.88 or 5.13 world.

As far as fuel economy goes, once you go that big, it is effectively gone for good - nothing can get it back. Simple physics. All that weight, aerodynamic drag and rolling resistance are going to take a lot more fuel. Stop worrying about mpg and enjoy how it looks.

 

With that large of a tire, you may want to seriously consider something a little steeper than a 4.33. A 4.56 ratio might be better for you.

 

I thought the 365 was a typo (never heard much of that size before) but if its not yeah you have to go for more gear. So if it is a 365/75 thats over 37.5" in diameter (c rated to boot) which basically equates to at least 4.88 gears.

 

I would go with 4.88's. You would be at 2059 rpm at 70mph with 4.56 and 2204rpm at 70 mph with 4.88's. Stock 4.10 gears with Factory 31" tires put you around 2210 rpm at 70 mph... Which is at the bottom end of your power band with the 5.4L. My stock 3.73 gears at 70mph with factory 33" tires put me at 1889... Which was sloth like . That is why I regeared mine to 4.30 to put me at 2178 rpm at 70 mph

 

Yep, I didn't read the part in his signature about the 5.4 engine, that changes my stance to going with 4:56 or 4:88 gears with a 37" tire.

-Mark