After reading all the threads I could find, I'm still can't figure out what ratio my 350 has. the door sticker has nothing on it under axle, but the tag on the rear end hsa a L30 on it. This beast gets 7 MPG around town, and it has 315/75r16's on for shoes, I'm thinking that the tires are too big for the rear end ratio, but I don't know...... what do you think?

I plan on putting 285'75r16's on , do you think it will help the MPG?

Thanks for any input, I'm kinda "not up on this stuff".

Ray

2000, F350, crew, v10, srw, 4wd, new to me.

 

I'm thinking that you probably can't see the 4 in what should be 4 L 30. I think sometimes the first number gets covered by the diff cover bolt

So I would say you have a limited slip rear, hence the "L" with 4.30 gears.


Hope this helps

 

DCSpecial is right on, and he killed two birds with one stone.

The 4.30 gears aren't helping your mileage any.

The 315's are probably actually helping you by effectively lowering your axle ratio.

Is your mileage always that bad? What are the temps like where you live? Then check the obvious stuff like air filter, fuel filter, brakes dragging, etc.

That and keep your foot out of it.

Waxy

 

Yes, that conferms my thoughts. Thanks. I am reading 2100 Rpm at 60 MPH. and I thought that would be a 4.10. thanks again.
4.30 is a little worse than expected... I'm in central Florida, hot is normal, esp in summer. and I'll rethink the tire change, again thanks.

Ray