285 75 16 1990 f250 stock?

[chillman88]

I wouldn't bother changing from 4.10 to 4.56 regardless. There's so little of a change. Lot's of guys change to 3.55 for mileage. Personally I like more gear, but I wouldn't spend that kind of money just for a couple hundred RPM. Especially since you're really not looking at a significantly larger tire. It's only an inch or so bigger than stock. A lot wider though.

 

[u2slow]

I have a 4.10 rear dif. Haven’t done much research on it but do you think I should regear it to 4.56 When I calculate my new tires in that’s what it should be just about. Any opinions?

I had 4.10 in my '95 F350 (PSD/5spd) and it liked the 35" tire upgrade. I would try the 33's first without re-gearing.

 

[The_Josh_Bear]

No reason to swap gears, it's much more work than paying someone to mount tires anyhow.
33" tires won't change your final drive nearly as much as a gear swap will. Keep the 4.10's and be happy, they will just give you a little longer legs for the most part.

 

[Shadetreemechanic]

I run 285s with 3.55 gears. Only time I notice is first gear with a heavy trailer, otherwise its fine.