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

[charlieaarons]

So I guess you’re going to air down 285/55s that have a sidewall height of ~6.2”. Whereas 285/70R19.5 and 305/70/19.5, both with enough load capacity to be useful as singles for a 550 type application, have sidewall heights of 7.8” and 8.4” respectively. Admittedly the X.5 wheels (16.5, 17.5, 19.5, 22.5) have crappy bead retention.
You should know that footprint increase with deflation is highly dependent on sidewall height and inversely dependent on wheel diameter, diameter being equal.
Although you stated “no serious offroad”, you rejected 19.5s partially because “can’t be aired down”. BTW Peter of Peter & Margaret in Australia with an Oka has had good results airing down 305/70R19.5s.
But I guess it’s a done deal.
Good luck.

 

[Vampergt4]

Sorry, what I meant to say is that I can run the Toyo’s at 65 psi on the paved road vs 90 or 110 PSI on the stock 19.5. Most of my driving will be on pave with some fire or gravel roads. Just that alone made a huge difference. Not sure it makes sense to air down those tires for off road (or gravel road) as there is not much sidewall.

 

[G35Vortec454]

Whoever told you 19.5 duallies cannot be aired down, they are selfishly trying to sell you something else or to mislead you knowingly or unknowingly. I've driven 12k-lb 4x4 motorhomes with 245/70R19.5s in deep sand or gravel or mud in Baja, airing down to as low as 11psi to get out of buried rear axle situation. Of course, aired down in mud didn't help and instead caused one of the duals to lose its bead when it hit a tree stump. I've also experienced rock between duals situations, without doing damage to the tires; actually, a bystander noticed the rock. Just be proactive checking when driving in rock country. Needless to say but I'm a fan of 19.5s for my heavy rigs; they are indestructible when in good condition. They're regrooveable and due to their thick tread can even be given additional big sipes for better offroad performance. I'm currently running 2004-old Goodyear 670 RV tires in my current Class A 4x4 rig, no tire cracks nor weathering. Don't believe everyone, including me. Me, I'm just telling actual facts/experience.

UPDATE - I wanted to provide the forum with an update on my decisions that were based on research and many conversations with forum members.
The first thing I did was get the Overlander weighed. It was full of water and everything that we would usually carry (total weight was 15800). The best piece of advice I received was to get rid of the 19.5 rims and tires as they are a commercial truck tire with steel carcass and cannot be aired down. After many hours of research and phone calls, I could only find 1 alloy wheel that was available that could carry the load and fit without requiring a lift. I ended up purchasing seven 22” Mayhem Challenger wheels in matt black rated at 4000 lbs each. As for tires, I researched tires that could carry the load but wanted a winter rated off road tire. I ended up getting 7 Toyo Open Country AT3’s in a 285/55/22. The reason for this size was to stay stock height as I’m not planning on any serious off road. I also replaced the stock Ford shocks with Bilstein’s and added front and rear summo springs.
All I can say is WHAT a difference, I have all the tires set to 65 PSI and the bone jarring when crossing bridges is a major improvement. After doing more research and knowing that one of the major problems are the rear springs that are too stiff. I sent all my specs to Deaver and had them design a custom set of springs for our specs. They are now on order and can’t wait to see the impact they will have as they will be a progressive spring. Stay tuned and I will provide an update in the spring once they get installed.
Sorry for the pics being sideways, they are not on my phone but turn when I upload them. View attachment 693040
View attachment 693037View attachment 693039

 

[mog]

19.5 (and 16.5) have the same bead area profile as the 22.5 rims, so bead retention is about the same.

 

[charlieaarons]

Did you mention “steel casing” because it “can’t be aired down”, or is there something else wrong with steel casings?
Believe me, when any tire (like my 395/85R20s) is aired down to about 25% of road pressure, the footprint increases - a lot. Steel casing tires, even as small as 7.50R16 or 235/85R16, have thick rubber in the sidewall, relative to their polyester counterparts, which people mistakenly think makes them “stiff”. Needless to say, thick sidewall rubber is good when aired down if one doesn’t like sidewalls ripped open by rocks or stumps.
In 300,000 miles of driving on steel casing tires over 50 years, lots of it off made roads, I’ve had exactly 1 tire get destroyed. By a broken shock absorber shaft’s lower half falling over to the side and eating the sidewall like a lathe. Certainly not the tire’s fault.
PS: in case any readers think otherwise, in a tire, the air carries the weight, not the sidewall. Polyester XL or LT tires often have an extra ply. It’s there to withstand the higher air pressure that’s required to carry the extra weight.

 

[tmckenna13]

Does anyone have any real world experience with bead retention of "consumer" tires vs commercial tires? I know pretty much anyone who travels to central and south america uses commercial tires for availability so I imagine they tend to do fairly well in most real world applications

 

[180out]

i run toyo 19.5" at 50 psi in the dirt all the time. duels in the back have not been an issue to date. i like having 3 spares knowing i can run a single in the rear if need be. 19.5 is a very popular tire size so finding one in a pinch would not be to hard. i have not rolled a bead to date. i run them at 105 on the asphalt. i am 8 tons fully loaded.

 

[tmckenna13]

i run toyo 19.5" at 50 psi in the dirt all the time. duels in the back have not been an issue to date. i like having 3 spares knowing i can run a single in the rear if need be. 19.5 is a very popular tire size so finding one in a pinch would not be to hard. i have not rolled a bead to date. i run them at 105 on the asphalt. i am 8 tons fully loaded.

I mean considering many commercial tires have tens of thousands of pounds of load on them at any given time I cant imagine that bead retention is a prevalent issue, but I've seen it mentioned a handful of times so I was a bit concerned.

 

[180out]

many things become "facts" only from repetition.

 

[charlieaarons]

Bead retention IS an important issue when running at very low pressures, like 25-33% highway pressure. And the 16.5/17.5/19.5/22.5/24.5 don’t do as well as 16/18/20” tires/wheels at low pressures. For easily describable reasons.

 

[tmckenna13]

Bead retention IS an important issue when running at very low pressures, like 25-33% highway pressure. And the 16.5/17.5/19.5/22.5/24.5 don’t do as well as 16/18/20” tires/wheels at low pressures. For easily describable reasons.

But where is your proof? I understand that in theory, the bead profile of the commercial tires could hypothetically, lead to poor bead retention but I've had a handful of people, such as 180out above, tell me, from personal experience, that theyve never had issues with bead retention at reasonably low pressures. Hell "NeverEnough" said the 24.5" DRW commerical tire setup he has on his 25,000lb international rig were vastly better than his 20" SRW with Michelin XZLs he was running originally. It seems like everyone jumps right to the 20" military beadlocks because of all the "cons" people associate with commercial tires. I get it, the whole "do it right, or do it twice" mentality but most of these vehicles aren't cookie cutter setups and what may be ideal on one rig might not be on another.

 

[180out]

For me the choice of tire/rim options that can handle my weight are limited. unless i want to move into super singles with 40+" tires. i am already 146" tall and the thought of 5+ more inches of tire and lift kit is not appealing. not to mention the body mods to clear the big tires. let face the facts F550, 17k pounds, 22 feet long, and 12' high. my rig is not a jeep or taco and i know this. The time and money i have invested is never far from the front of my mind. i use topo maps, plan my routes, and know the limits of the truck. we never have an issue getting to the places we want to go. the goal is multi day trips to where there is no one else for miles. All that said I'm not doing anything very fast. i crawl around on two track dirt roads 15-35 mph max. in our playground which is the the wilds of the Nevada/CA desert. the risk of rolling a fount bead off while in some full stop high speed turn is low. i like the cost, availability, and ride that the 285/70 R19.5 (35") provides me. at 50 psi the ride is smooth and the pig does well in soft soils. i have never had an issue with the duels or rocks in over three years of dirt roads. i did my own analysis, looked at the cost and availability of all the options, weighed the pros-cons and here I am. running through the desert with 7 tires i can change and repair my self. To each there own.

 

[charlieaarons]

But where is your proof? I understand that in theory, the bead profile of the commercial tires could hypothetically, lead to poor bead retention but I've had a handful of people, such as 180out above, tell me, from personal experience, that theyve never had issues with bead retention at reasonably low pressures. Hell "NeverEnough" said the 24.5" DRW commerical tire setup he has on his 25,000lb international rig were vastly better than his 20" SRW with Michelin XZLs he was running originally. It seems like everyone jumps right to the 20" military beadlocks because of all the "cons" people associate with commercial tires. I get it, the whole "do it right, or do it twice" mentality but most of these vehicles aren't cookie cutter setups and what may be ideal on one rig might not be on another.

Debeading is a very unpleasant experience. I am personally unaware of the existence of any bolttogether wheels of those sizes with the ability to install an internal beadlock. Which is the only guarantee against debeading at low pressures (again, 25-33%) whilst in mud, rocks, hard turn of steering, etc. Hate to be repetitive, but debeading tends to occur in really messy environments. I knew someone would call me on this.
If such xy.5 wheels exist, especially in 22.5, please inform me.

 

[tmckenna13]

Debeading is a very unpleasant experience. I am personally unaware of the existence of any bolttogether wheels of those sizes with the ability to install an internal beadlock. Which is the only guarantee against debeading at low pressures (again, 25-33%) whilst in mud, rocks, hard turn of steering, etc. Hate to be repetitive, but debeading tends to occur in really messy environments. I knew someone would call me on this.
If such xy.5 wheels exist, especially in 22.5, please inform me.

Commercial wheels and tires much higher pressures on road than consumer tires, same is true offroad when aired down. As 180out said his "aired down" pressure is 50psi compared to a consumer tire that is usually aired down to somewhere in the neighborhood of 20psi. I can't imagine that debeading a tire with 50psi of air in it is all that easy. I know, Murphy's Law anything that can go wrong will, but I've heard horror stories of MRAP beadlock wheels leaking constantly, not having orings, not being able to buy orings, etc. The 20" military tire method is not perfect and to be honest I don't think a lot of folks utilize their rigs to the point where the beadlock is necessary. I've ran 20" Light Truck Tires at 12psi with a decent load and no issue, I wasn't rock crawling to be fair, but in my opinion beadlocks tend to be overkill in the vast majority of non military applications.

 

[mog]

20-inch beadlock and 22.5 rims are apple and oranges. If you are a hardcore Unimog explorer like charlieaarons then 20 inch bead locks are the way to go so you can go 20psi or lower to get a huge footprint. 22.5 rims are good for tire availability and more road worth tread if that is what you are looking for. I have/had both 20" Hutchinson (not beadlocked) with XZLs on my MB1017 and 22.5" Alcoa with Ironman I-402s on my C4500. I have been on a quest to get the lowest pressure on 22.5 tires since getting my C4500. The European Expo community seems to be split about 50-50% on 20" and 22.5" in the big truck category. The consensus I have gotten from them, (users, engineers, professional builders), is a low of 40 psi is 'safe' (with the more cautious staying at 50psi) and 30 psi is pushing it for the 22.5s. While with beadlocks, into the teens is doable with 20" rims (much safer with beadlocks!). Most of the 'low pressure' usage in the 22.5s is to get a better ride on rough roads as opposed to getting a 'large footprint'. From real-world testing with my 1017 (at 9 tons with the camper) on 20"s and the C4500 (at 8 tons with the same 2 ton camper) on 22.5"s neither the XZLs nor Ironmans got much tire bulge (footprint increase) at 40 psi. I think the trucks are just not heavy enough with the tires rated (for 4) in the almost 40,000 lbs range. From my experience, a lot boils down to what rims you can get for your truck, or what it has. My 1017 already had Hutchinson/XZL so perfect, and the C4500 already had Alcoa/Ironmans so perfect again. I don't feel lacking as where I am going to drive my 8-9 ton 'house' is limited by my desire/precaution more than the tires on the house (that is why I bought a Gladiator). As always YMMV.