IA_F150

I'm very close to pulling the trigger on a 2019 Roush Supercharged F150 5.0L 4x4. The truck will be used as a daily driver and will be driven by my wife and son on somewhat rare occasions. I don't plan to ever track it or anything. A few times a year I'll tow a smaller enclosed dual axle trailer with a decent load on it. Combination of town and highway driving. I don't want to have it geared so low that I can't ever take off without spinning.
The truck will come with 275/55R20 tires but those will be replaced with General Grabber ATX 305/55R20 by Roush.
My axle ratio options are 3.15, 3.31, 3.55, and 3.73. I also have to select Electronic Locking or Non-Limited Slip.
I'm leaning toward 3.55 electronic locking but I'd love to hear your opinions. Keep in mind the truck will have 650 HP & 610 ft-lbs.

BadCon

There are a couple variables here. #1. The TVS blower used by Roush makes a lot of torque. #2. the 10r80 can makeup for quite a bit of gearing. #3. The tires used by Roush are 33", slightly larger then the stock 32".

If you are going to keep the 33" tires, then 3.55 wouldn't be a bad option. I have a 2016 Roush supercharged truck with the 6r80 transmission and 3.73 gears, and traction is impossible to find in 2wd in 1st and 2nd. I'm using summer performance tires, but I also have a custom tune and more go fast parts so I'm making more power then a stock Roush kit. If you were using stock sized tires I'd say go 3.31 due to the torque profile of the TVS, but those 33" tires are heavy.

PerryB

I think you're spot-on with your 3.55 selection.