Looking for Tire Info, 2002 Ford F450

[brp]

I've got my F450 vs F550 for Poor Man's Earthroamer going on the boards but now I am looking for some specific advice from you guys on tires and suspension.

Toymaster has been really helpful in pointing me in the right direction to clear 42" MPT81's, and I am pretty set on that direction.

However, expeditionimports has a sale on the 39" that would save about $1,000 on the tires. I am wondering then about suspension. If it only takes a little suspension work to clear a 39" tire, and the tires are cheaper, that is intriguing. Super singles.


I am hoping those of you with 1999-2007 Superdutys and larger tires can weigh in and tell me things like:
-What tire (size/brand/model)?
-What suspension, lifting or trimming changes did you have to make?
-What rims are you using, factory, Rickson, other?
-Costs, if you feel like sharing.
-Are you happy with the end result?

-Pictures!!!!!

I'm asking for a lot here, but it could be a big help to others as well.

Any info would be much appreciated and thanks.

 

[Kaisen]

Are you referring to the closeout 275/80R20 MPT81's? Versus the 335/80R20 MPT81?

The considerations beyond cost are gearing, load, and road manners

The 275s are 10.1% smaller in diameter and 9.2% smaller in rotational circumference than the 335s. This means that the 275s rotate 50 more times per mile than the 335s. Since the typical F450 has 4.56 gears and the F550 has 4.88s, this comes close to negating that difference. The F450 4.56 on 275s will turn 1750 rpm at 60mph in top gear, where the F550 4.88 on 335s will turn 1700 rpm. Something to think about.

The 275s are rated at 4674 lbs per tire, where the 335s are rated at 6779 lbs. With four tires, that's a 8420 pound difference in load capacity. That could be a considerable safety margin.

Road manners will be considerably different between the two, as you're four inches wider stance on the road with the 335s. That width could be a difference in how stable it feels laterally, especially with a high-center-of-gravity loaded rig. Ride and low-pressure compliance is different as the 335s have an additional 2" of sidewall between the wheel and the ground (or tire and wheelwell). They can flex over an obstacle easier.

Suspension mods will be different depending on model. Asking someone what they did to their 2003 F250 or 2005 F250 will give you different answers as one used leafs and the other coils. It will be different between a F450 and F550 as well. If you're considering a 7.3L (1999-2003) 4x4 F450 or F550 then make sure you get relevant info on those two specific trucks. Other Super Duty versions won't be relevant.

 

[brp]

Thanks for the very useful reply Kaisen.

Yes, I am referring to the 275/80R20 and 335/80R20 MPT81.

In regard to gearing, if the tire gives me what I need, then great. I would like to get the overall best tire for my needs and then re-gear should I need to. With the 335 on the F450, I should be looking pretty good. The seller thought it had 4.33 gears, but was not sure.

The 275's still give me 18,696#s of capacity, 3,696#'s more than the GVWR of the truck. That seems to be plenty of margin, if the trucks weight is evenly distributed front to back. The rear axle is rated to 11,000#. With my short wheel base and water tanks mounted toward the front of the camper, I should have a better front-to-back weight distribution than most campers. Any thoughts there?

I do like the added width/stability of the 375 and obviously the off-road capabilities.

I was not sure about when the suspension changes were made and what parts/concepts are interchangeable from, for example, a 350 to a 450.

Icon seems to have the products to lift my leaf sprung 450 5 inches, although they do not advertise a specific kit, with a few exceptions. (sway bar links, rear u-bolts, pitman arm)

Thanks

 

[brp]

I just looked at the Nitro Gears build thread, as Redthies suggested. They fit 42's with only about 2.5 of lift and some fender cutting and flares from Bushwacker.
I am basically in the same situation as them where the front is the real challenge, because the on the rear I can just cut the flatbed to fit. That thread is here:

http://www.expeditionportal.com/for...-Ford-F450-4x4-Motorhome-on-42-s-Build-Thread