Earthroamer Tires

[jwild]

ER tires, incl. in Baja

I was an early EarthRoamer owner. Began with the Goodyear MTRs, which were on the spec.s definitely overloaded, but by monitoring the interior temperature we never had any problems. Later used Toyos, but the thicker sidewall retained heat to such an extent that we could not drive at highway speeds. Had to dump them.

We drove all over Baja (beaches, Agua Verde, San Juanico to Loretto thru the mountains, etc) with no problems at all.

The new Alcoa rims with 22.5 tires are an improvement on the highway, and air down (35 front, 45 rear) surprisingly well, giving VERY GOOD off road traction.

 

[Scott Brady]

The current tires are quite impressive in the dirt, especially when aired down. They may not look that large on the vehicle, but measure nearly 37", which does a good job of providing differential clearance and rolling through ruts and ditches and over rocks.

We have now tested the XV-LT on the entire length of the Mojave Road and El Camino del Diablo.

Some exciting changes are in the works too.

Oh, and John, it is nice to see you on Expedition Portal!

 

[expeditionvan]

"Some exciting changes are in the works too."

Hello!, Can you please follow-up and or elaborate on said 'changes'?
Chassis? Cab? etc.
Thank you.

 

[jgolden]

What improvements does Earthroamer have to do to fit the 22.5 Alcoas SRW? I know it's a different lug pattern, do they run stock axles, hubs, brakes???

I own a 2001 f-450 4x4 and I'd like to do the same tire wheel setup and lose the "dually" section of the bed. Can someone give me a step by step of the process and point me in the direction for parts? This setup seems to be the best option for a SRW conversion.

Thanks
James

 

[boblynch]

James, I've been considering a F550 SRW conversion for a while. Most of what I've found may be found in the following thread
http://expeditionportal.com/forum/showthread.php?t=12380

I know Earthroamer uses the OEM axles and a custom spacer on the wheels to correct the track. Not sure about other modifications required for the SRW.

Keep us posted on your decision. I know of several other ExPo members that would also like to do this.

Bob

 

[jgolden]

Thanks for the info Boblynch. From the research I've gathered, it seems that 22.5" Alcoas are the best option - just like the EarthRoamers use. The Alcoas are strong, I assume lighter than most other wheel options and the tire size is ideal for me - 37".

19.5" uses skinny tires with hard side walls with limited tire sizes.
20" steel wheels are too heavy and most tires I've seen are 40" or bigger!!!

I'm still wonder as to what ER does to make the 22.5", 10 lug wheels work on a F-550????

anyone know details????

 

[haven]

I think Earthroamer uses an 8 bolt to 10 bolt adapter to mount the 22.5 inch rims. The adapters are about 3/4 inch thick. The photos I've seen of the new ER show the front wheels sticking out beyond the fenders about that much.

Maybe you'd need to move the 22.5 inch wheels out that far to fit the same wide tires on the front as well as the back.

I think Alcoa will make a custom wheel to your specifications (probably very expensive!). If true, you could get an 8 bolt pattern and the correct offset to fit the tires. The 8 bolt pattern would work because you're not changing the GVWR of the truck, just the wheels and tires.

Chip Haven

 

[charlieaarons]

F450 and 550 have 10 lug studs.
Given equal strength and width, a 22.5 wheel will be heavier than a 20. Why? 2.5" more metal. Of course, aluminum is lighter than steel. Conversely, Michelin 11R22.5 is 12 lbs lighter than a same ply rated 11.00R20. Why? 2.5" less rubber & steel.

Charlie

 

[jgolden]

Charlie - What would your recommendation be for the F450/550 SRW?

Also, does Alcoa make a 20" wheel? Do you agree that an Aluminum wheel is a better option than steel for this setup?

Is there a tire out there that's about 37" X 13.00 for a 20" wheel?

Thanks in advance

jg

 

[charlieaarons]

For highway: stock tires
If trying for SRW, highway: something on 19.5 or 22.5, there are innumerable choices.
SRW, offroad biased: 335/80R20. Either Michelin XZL 141K, or, if more load capacity needed, Continental MPT81 147K. 4.88 gears must be specified and front wheel bearing longevity may be a problem. This size is what Westcott/Turtle V worked out to be the best.
If if you could get 17s or 18s to fit, nothing is made in sufficient load capacity. 16s definitely won't fit and only 325/85R16 XMLs have remotely near enough load capacity (137K = 10140 lb/axle).
141 gives you 11560 lb/axle; 147 = ~13200 lb.
There's one more thing I want to say: Why would anyone want to convert to SRW except for offroad abilities? And since that's the only rational reason I can think of, why not get the widest largest lowest pressure tire that will work? IOW a 335/80R20, not a 295/60R22.5. The footprint difference is 109 sq in @62 psi vs. 70 @ 131 psi.

Charlie

 

[boblynch]

Charlie's analysis is correct, 20s are a better solution offroad than 22.5s. Also, the F450/F550 is a 10 bolt pattern.

I'll try to shed light on the question of why would Earthroamer use the 295/60R22.5?

IMHO the answer is probably some combination of max. payload, max. speed, tire availability, and roadside emergency replacements. The Michelin 295/60R22.5 exceeds the payload needs of the Earthroamer, is rated for 75mph, is readily available, and has a vast number of siblings that could be used as a roadside emergency spare. Is it the best offroad tire? No. Will it meet the needs of most Earthroamer owners? Yes. Is it the best business option available to Earthroamer at this time? Probably.

From all accounts I've read the Michelin XZL 335/80R20 is a superior tire for a SRW application. See http://www.turtleexpedition.com/news/index.php?news=9 for the Turtle Expedition's view on this subject. Also, read the many previous posts by Charlie and others on this subject.

However, as a novice considering a SRW conversion, my biggest concern is availability. The XZL is hard to find in North America. While it may be possible to track down a set now, will that be true in a few years? The Michelin website does not list this size (http://www.michelintruck.com/michelintruck/tires-retreads/tireInfo.do?tread=XZL ). Truth is many web searches for XZLs will take you to this thread before they will somewhere that has them in stock. This doesn't make the 22.5s perfect, but sure makes a guy think twice (or in my case about 1000s times).

Bob

 

[boblynch]

An Earthroamer owner (Expo member JRhetts) mentioned in another thread that his new ER will include 20" custom wheels to accommodate Continental MPT81s after a 3" lift.

 

[JRhetts]

ER Tires -- 22.5 and 20 inch rims

I'll go ahead and chime in here. I'm NOT technologically knowledgeable; Charlie and many others know a whole lot more about tires and specs than I. What I hope I can contribute is a user's experience.

ER uses a very strong 22.5" Alcoa rim - rated at 10,000# each. [Parenthetically, strong, tested rims are very important to me, as I have cracked 3 rims in my expedition camper career, 2 at one time, which stranded me in the Southern Oregon desert. More than inconvenient, this was dangerous and not something I want to repeat.] While the rim is a 10-bolt pattern, it is not the same as the Ford pattern. So they use a heavy, steel adapter plate between the Ford holes and the Alcoa holes.

ER has used a few different 22.5 tires, from Bridgestones to Michelin. We drove the Michelins, steer tires in front, drive (unidirectional) tires in the rear, for roughly 30,000 miles.

On highway (where, let's face it, an awful lot of our mileage occurs getting to and from the places we really want to be) the performance was excellent. Handling was crisp and precise, noise was minimal, and they can run and run at virtually any temperature and any speed. Both my wife and I felt relaxed and safe driving them on pavement. None of the "slop" or vagueness we knew with the original MTRs

Off-pavement, at highway pressures, the ride is fairly harsh; you don't have much in the way of sidewall and what's there is really stiff, as a highway tire should be. Nevertheless, we low-range crawled all over the alluvial fans of Death Valley at full highway pressure and never had any sidewall damage whatsoever (luck, or tire strength, I don't know.) However, aired down to 35/45, their performance improved very substantially. The ride smoothed out dramatically, and sand performance seemed to have a good margin of safety vis-a-vis plowing in and getting stuck. (We never did.) We drove our fully loaded ER pulling a horse trailer through literally miles of bottomless mud in Central Oregon, but that was with the MTRs. Our only real mud experience with the 22.5s were quite short stretches, and we had no problems - but truly it wasn't the same test. [You need to have a pretty good compressor to reinflate these big tires; I had very good luck with a PowerTank set up.]

In the process of ordering our new vehicle, I have been told that ER plans to offer a new option: 20" custom alum rims and the ability to use corresponding tires like the Continental MPT 81s. This is not at this time a promise or a foregone conclusion, as the rims are still being developed and will be subject to DOT testing [important from my point of view and experience.] The bolt pattern will correspond to Ford's, so no adapter plate or extra set of 10 bolts will be required. The tire diameter will increase from roughly 36 to 41 inches - both gaining under-vehicle clearance and necessitating a 3" lift (the wheel wells on both the Ford and the ER house are able to accommodate the increase without further issue.)

With the new combo, an ER's off-pavement performance margins should be improved substantially, though the effect on higher-speed on-pavement handing is less certain (esp. noise and steering precision.)

Th...Th...Th...That's All Folks.

John

 

[haven]

335/80r20

Interesting news that Earthroamer may adopt a 20 inch rim. The Continental MPT 81 335/80R20 (12.5 R 20) tubeless tire is the closest to the 41 inch overall diameter mentioned.

The Ford F550 is available with a 5.33 axle ratio, which is about 10% lower than the 4.88 ratio in the Earthroamer today. The switch from 37 inch tall tires to 41 inch tires is about 10% larger in diameter so the overall performance should remain the same.

The inflation table below shows that at 60 psi the 335/80R20 tire can support 10,000 lbs on the rear axle. This relatively low pressure should mean improved offroad performance and a more comfortable ride.

Here's what the current earthromer tire looks like

And here's a 335/80R20 Michelins on a Fuso FG with susupension lift

Chip Haven


Stats about this tire from the Continental tire guide:

load index 147 (3075 kg, 6779 lbs)
speed rating K (110 kph, 68 mph)
recommended rim 10, 11 in
width maximum 354 (13.9 in)
outer diameter maximum 1076 (42.3")
Continental width rating 310 (12.2")
Continental outer diam rating 1032 (40.63")
static diameter 960 (37.8")
rolling circumference 3120 (122.8")

single tire weight capacity at pressure

2.0 bar 1320 kg 2910 lb 29 psi
2.5 bar 1575 kg 3472 lb 36 psi
3.0 bar 1800 kg 3968 lb 43 psi
3.5 bar 2000 kg 4409 lb 51 psi
3.75 bar 2120 kg 4674 lb 54 psi
4.0 bar 2240 kg 4938 lb 58 psi
4.25 bar 2335 kg 5148 lb 62 psi
4.5 bar 2430 kg 5357 lb 65 psi
5.0 bar 2625 kg 5787 lb 73 psi
5.25 bar 2710 kg 5975 lb 76 psi
6.0 bar 2975 kg 6559 lb 87 psi
6.5 bar 3075 kg 6779 lb 94 psi

 

[boblynch]

Chip thanks for the tire summary. Unfortunately the 5.38 axle ratio is only available with the V10, not the diesel. It's also worth noting that the factory options for heavy duty 200A alternator, dual 160 alternators, and dual fuel tanks all require the diesel.