tire size help.

[jmeaby]

I'm getting ready to lift or level my truck, but my question is if i put 35 or 37 inch tires on do I need to have my differential gears changed? I'm not sure what I have from stock but it is a stock suspension so I assume so are the gears I have a 2004 f250 265/75/16 tires on it now. And how big could I go with just a leveling kit?

[jmeaby]

Is there another section I should put this in?

[layson]

I ran factory gears for a while with 37's. Great mileage and honestly if you don't tow much it isn't a bad setup. Best thing to do is just stick the tires on their you want and see how you like it.

Oh and I just realized you are going to run a leveling kit. Forget about the 37's then... LOL. You could probably squeeze the 35's in there.

[jmeaby]

It's either a lift or leveling kit. I wasn't sure about the factory gears. I want to lift it with 37 so like a 6 inch lift I'm thinking. So you didn't mind it with factory gears? I heard ppl really complaining about that on another forum.

[layson]

6" would do it. It is a toss up on weather you like it or not. If you spend a lot of time on the freeway going 75 mph than you will probably love it. I think I was at 83 mph at 2000 rpm's. So when you are in overdrive doing 65-70 it can be bogged down. Especially if you find some hills. It didn't really bother me so much, I would just manually shift it if I needed to or just take it out of OD.

If you spend alot of time towing, then you might hate it... mainly because you would be at 65 mph and that isn't the sweet spot at 2000 rpm's anymore. I can't remember what the rpm it was at when it wasn't in OD.

It is one of those deals that you just go for it. Then drive it and see if you like it. Then down the road you could have it regeared. Or go down to 35's on the 6" lift. I don't think that looks bad at all. Especially with a 15.5" wide tire

[Karls03]

Originally Posted by jmeaby

I'm getting ready to lift or level my truck, but my question is if i put 35 or 37 inch tires on do I need to have my differential gears changed? I'm not sure what I have from stock but it is a stock suspension so I assume so are the gears I have a 2004 f250 265/75/16 tires on it now. And how big could I go with just a leveling kit?

Stock gears are most likely 3.73. If UNCORRECTED speedo says 70@2000, it's 3.73.

Leveling kit, 35s depending on wheel width, I really don't think a 10" wheel will cut it there.

As mentioned, 37s means 6 inch lift.

What gears? New tire/old tire= rate of change. Then rate of change x existing gear=new gear. Keep in mind that tires are RARELY advertised height.

36.6 / 31.5 = 1.162
1.162 x 3.73 = 4.33426.

So, a 4.30 gear and a 37 inch tire should keep the speedo pretty close to where it is now since you would not be changing the reluctor gear that the ABS gets it's input from.

I'm pretty happy with my 3.73/35 set up. Speedo and odometer are off, but that's nothing that a GPS and a calculator can't help me with.

[jmeaby]

I'm pretty sure I have seen them leveled with 35's not sure. They loomed a little big for the 33 they say it would fit. How if I wanted 35s how wide would u go?

[Karls03]

It depends, on an 8" wheel, 35s will fit fine. But I don't like a 315 tire stretched over an 8 inch wheel.

I have about 4~5 inches up front and ended up pushing my bumper 1.5" forward. I can contact my trailing edge opening going into a parking lot if I turn it just the right way. But I have 16x10s with 4.5" back space (pretty standard 99-04 wheel).

sent from a dumb guy with a smart phone

[jmeaby]

Well I called about getting a 4 inch lift I have a quote for a bds installed at 1800. And rough country ball park 1500ish I have to pull a 5th wheel next year and i have heard of ppl towing with that lift. I think that's what I'm going to do

[JasonY]

You're gonna be really hurting on towing power with 3.73's and 37s.

Jason