Gears for 40 inch tires

[Mach1mike]

Looking to get 40 inch tires on my 2018 super duty with 3.55s currently. Trying to decide between 4.56 or 4.88. I dont tow truck is just A weekend warrior and trips out of town now and then. Like some recommendations.

 

[Addicted4]

New tire divided by old tire times gear ratio will give you new gear ratio

Ex: 40/34x3.55 equals 4.17 gears to put you at stock

 

[Lt.Dan]

I would get 4.30s, it'd be a nice match

 

[BIG JUICE]

That’s bad math. Actually need to use the final gear ratio.

 

[Addicted4]

Math doesn’t take into consideration of rotating mass so 4.17 would compensate for tire diameter. Like stated 4.30 is what I would go to.

 

[Mach1mike]

I have a 32 inch tire from Factory probably going to go with the 456

 

[Addicted4]

What is your factory tire size?

 

[Mach1mike]

32 inch