I have Yukon 4.56 on my 06 F150 FX4 on 35" BFG All Terrains and it is way TOO MUCH GEAR for that size tire and any sort of highway distance driving.. Wish I stayed with 4.10's since I had no intention to go with 37" tires since it cost over $2000 for the front, rear, full rebuild kit and labor.

I always tend to find things out the hard way...

 

I would choose 4.10,4.56 might be to low if your not planning on going over a 35" tire.If you know you will go with 37",then get 4.56.........Later I am planning on a gear swap,having 37" tires,I will go with 4.56.

 

Sorry kddsRam:/ But thank you for your testimonial. That alone makes me think 4.10 will be just fine then.

 

I just got 33" tires over the stock 31" tire size but am still running 3.55's and having a 2.5" lift. I have to say I am happy with the 3.55's. They give me good highway mileage and the 400+ hp engine has more than enough power to move this beast! I wouldn't consider regearing unless I went with something bigger than 35's. I also don't tow much.