Newbie needs assistance with tire choice for new to me 2020 F550 4x4 Overlander

Kolockum

Adventure Nut
Why do you say that?

I think he is referring to the lack of availability.

When planning my vehicles I always pay close attention to what Gary and Monika Wescott from turtle expedition have done on their rigs over the years. They are the grandparents of overlanding. On their F550 they started out with 20" rims but have gone to 22.5" rims for a larger selection of tires. IIRC in an interview Gary also said 22.5 was easier to find in other countries and when running 20's he had a plan to get tires shipped to him if necessary. Tons of information on their website (but requires some digging). https://turtleexpedition.com/vehicles/turtle-v/
 
I think he is referring to the lack of availability.

When planning my vehicles I always pay close attention to what Gary and Monika Wescott from turtle expedition have done on their rigs over the years. They are the grandparents of overlanding. On their F550 they started out with 20" rims but have gone to 22.5" rims for a larger selection of tires. IIRC in an interview Gary also said 22.5 was easier to find in other countries and when running 20's he had a plan to get tires shipped to him if necessary. Tons of information on their website (but requires some digging). https://turtleexpedition.com/vehicles/turtle-v/

Interesting. I guess I just figured that 20" tires would be easy to find anywhere.
 

Joe917

Explorer
20" tires are unavailable in South America. We met two heavy trucks on 20" tires with no spares left, desperate for spares.
 
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I think he is referring to the lack of availability.

When planning my vehicles I always pay close attention to what Gary and Monika Wescott from turtle expedition have done on their rigs over the years. They are the grandparents of overlanding. On their F550 they started out with 20" rims but have gone to 22.5" rims for a larger selection of tires. IIRC in an interview Gary also said 22.5 was easier to find in other countries and when running 20's he had a plan to get tires shipped to him if necessary. Tons of information on their website (but requires some digging). https://turtleexpedition.com/vehicles/turtle-v/

Also I wouldnt do 22.5 tires. I do a lot of soft sand driving on local beaches here and need the biggest sidewall possible for airring down.
 

Joe917

Explorer
20" tires not available in South America, period. You could try to import them, but by the time they clear customs your visa would have expired and you would be out of the country! 22.5s air down too. There are many options but if a long term trip in South America is planned don't pick 20" rims.
 
20" tires not available in South America, period. You could try to import them, but by the time they clear customs your visa would have expired and you would be out of the country! 22.5s air down too. There are many options but if a long term trip in South America is planned don't pick 20" rims.
19.5s okay in South America?
 
Just a thought but if you are planning a trip through South America you could bring 19.5s as spares, (1 inner and 1 outer) obviously with the same rolling diameter. Best case scenario you never have to use them. Worst case scenario you get a flat on the 20" wheels swap on a 19.5, then get a flat on that, and have to have the tire replaced.
 

Joe917

Explorer
I can not tell you about 19.5. All I can confirm is 20" tires are unavailable and 22.5 is readily available.
Running dual rears is not optimal. The vehicle tracks poorly in sand and mud, rocks tend to lodge between the tires and you cannot air down duals. You are also wearing 4 tires instead of two. The only reason to run duals is if you cannot get tires with the load capacity to run singles.
 
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shortbus4x4

Expedition Leader
What are you doing about ULSD fuel and DEF in South America? Do you know if there are Ford dealers on your route that have the technology and training to work on your engine and after treatment if something fails? I'd be more worried about that than tire availability.
 
I can not tell you about 19.5. All I can confirm is 20" tires are unavailable and 22.5 is readily available.
Running dual rears is not optimal. The vehicle tracks poorly in sand and mud, rocks tend to lodge between the tires and you cannot air down duals. You are also wearing 4 tires instead of two. The only reason to run duals is if you cannot get tires with the load capacity to run singles.
Whats wrong with airring down duals? Plenty if people do it here on long island to drive on the beach. Main reason I would want to run duals is in the instance if a blowout. I feel like a blowing out a super single would be terrifying, dangerous, and in many cases damaging to the rig, whereas with the duals it would be mostly a minor inconvenience.
 

Joe917

Explorer
When you air down duals the sidewalls touch causing friction, overheating and even failure. A blowout of a dual on a loaded vehicle will often cause the failure of the second dual as well.
 

DirtWhiskey

Western Dirt Rat
I've blown out duals in a pair at highway speed before. That's not as fun as many people seem to imply. Ripped up the well and took out a spring perch. I can see at low speed how they have a safety factor but Joe917 is right. Any loss of a dual leads to an unsafely loaded single if they don't both blow.
 
There’s multiple considerations for a F550. Conversion from duals isn’t simple. You need a reversible wheel, with offset that gets F/R track as close to equal as possible. While keeping additional stress on hub bearings minimized. By those criteria alone, hard to solve.
You don’t want to go >42” for reasons of gearing, tire weight and bearing stress. We have all sniffed rumors of occasional ER rear wheel bearing failure.
305/70R19.5 is at the low end of size ~36.5”), footprint (55 sq in), and load capacity (~6700 lb). And despite being 19.5 is an oddball size and could be hard to find.
315/80R22.5 is ubiquitous but too big (43”). 295/80R22.5 is 41.5” tall, ~7000 lb capacity and 80 sq in footprint. In the Goldilocks zone, like earth. 8.25-9.00 wheel width.
Of course 335/80R20 is perfect except hard to source. Even higher load capacity, and up to 109 sq in footprint. And 2.5” taller sidewalls, rims have better intrinsic bead retention, compatible with beadlocks and maybe even Hutchinson rims. And isn’t the biggest point of the exercise flotation and ability to safely use low psi?
My solution on my vehicle (U500) is 395/85R20 rather than 445/65R22.5. I carry a second unmounted spare (sort of the ultimate solution to the availability problem).
After all, would you venture into the middle of the Kalahari or the Chaco with only one spare? I had a sketchy used replacement tire I found in Tucson blow out at 15mph in Saline Valley and I didn’t enjoy not having a spare after that. Just prior to that we were in mid Baja and an aftermarket Koni broke in half and the lower half of the shaft destroyed right rear sidewall like a lathe. We had turn around and head for the border with no spare.
Mounting a big tire yourself is never fun, but it’s at least physically possible with Hutchinsons. And any tire shop anywhere in the world can mount a tire as long as you have the tire.
Also please get over the issue with steel sidewalls. The effects on flexibility are nil at the loads we are dealing with and there’s no such thing as a organic fabric sidewall radial LT tire) that can deal with >~4500 loads per tire. Flexibility is mainly a function of load vs psi, and very importantly sidewall height.
My bottom line advice: get the best tire and wheel to do your job, carry a second unmounted spare. Or more.
Even one extra spare gives the critical gift of TIME to get another to the continent you’re traveling.
If you want a universal tire, get a 75 series Landcruiser with 7.50R16s (those aren’t so easy in NA anymore but 235s will substitute).
One afterthought: the bigger and heavier tires go the lower the speed rating. The 295s are 65-75 mph and usually more aggressive treads tend to be at the lower end of the range. 335s usually 68. My 395s 55-68 but for ~$2k each I can get new version XZL2 which are 68-75 depending on load.
The dream of driving 85 down the Interstate on oversized tires is just a dream.
 
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Vampergt4

Member
I think he is referring to the lack of availability.

When planning my vehicles I always pay close attention to what Gary and Monika Wescott from turtle expedition have done on their rigs over the years. They are the grandparents of overlanding. On their F550 they started out with 20" rims but have gone to 22.5" rims for a larger selection of tires. IIRC in an interview Gary also said 22.5 was easier to find in other countries and when running 20's he had a plan to get tires shipped to him if necessary. Tons of information on their website (but requires some digging). https://turtleexpedition.com/vehicles/turtle-v/
Thanks, this is great information and will look at their site.
 

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