My primary concerns on my new build is Stability at 70mph with the least amount of boost
Truck will be a XLT Super cab 4x2 w/3.55E So a 2.7 or 3.5 on 18's or 20's 2.7 on 20's? 3.5 on 18's?
I will not be towing just a recreational bicycle hauler
thanks for your comments guys

 

The F150s are quite stable at any legal speed, as long as top-heavy loads are not added. The rims will likely have a small, if any, effect on stability.

I would not be concerned in any of your described situations.

If you are concerned, there are a few things you can do to increase stability.

The longer the wheelbase is, the more yaw and pitch stability you will have. This is why the longer wheelbase trucks traditionally had higher tow ratings than shorter ones.

Heavier payload and tow ratings will require use of stiffer springs, shocks, and sway bars. These will all improve stability. The HDPP is probably the most extreme example of this, and would probably create the stiffest ride of any F150 combination.

 

20" wheels will feel the road better with the shorter sidewall than the 18" wheel offers.
I have 18's but wish they were 20 to reduce body roll.

Good luck using minimal boost. ha

I don't know why you are trying to pair an engine size to a tire size though.

 

you'll never be in the boost with a 5.0

 

Or with the 3.3L V6. Plenty of power to haul a bicycle and probably the best engine for fuel economy.

18" wheels and tires weigh less and will give better fuel economy as well.

 

I am still holding the opinion of that, unless you specifically want something offered by a different engine (generator, sound, Payload, tuned power, etc)...your default should be the 2.7

Also, given the choice, I don't think the surcharge for 20s is worth it at all.

2.7, 18"