SRW's for FUSO

[GR8ADV]

Optimum performance and world wide availability are often mutually exclusive and I have heard convincing arguments both ways.

-- Fuso fit these beasts with 750x16E tires in the US, duals on the back. This will probably give you the best load capacity and dead easy replacement almost anywhere in the world. PRO: Lowest cost, best performance on pavement (where you will spend over 90% of your time). CON: Some loss of off pavement performance, no cool factor at all.

-- There are various single rear wheel conversions. If you go with one, I would select one that has some form of track record and offers some form of guarantee. In this case, don't worry about tires and simply be prepared to ship a set when the time comes. PRO: Better off road performance. CON: Much higher cost.

Your money, your choice.

.

Hey if I wanted good, practical and sound advice I would have asked my wife. There is no place for that crap here.

 

[DiploStrat]

Practical? I am running a 298/70x18E on my Tiger. You can't find that over the counter in the US, let alone overseas. (Nice tire, though.)

If you want a take on 19.5 rims/tires, look here: http://www.travelin-tortuga.com/Travelin-Tortuga/our-vehicle/rickson-wheels.html

My take is that a lot of what they don't like comes from the combination of a narrow tread and a stiff sidewall. But a wider tire would, almost by definition, have a softer sidewall.

Again, your money. (Just trying to help you spend it! )

And wipe your feet before you come into the house!

 

[mog]

I'd throw in that the SRW conversion does much more then give you a single track for off-road.
The primary reason I when to SRW was to increase my tire diameter to reduce the engine's RPM in my highway cruise range of 50-60 mph.
I could not find (within reason) any tires that would mount on the stock rims with a diameter of 35 inches or greater.
I went with 325/80-16 Faulken Wildpeak A/Ts (listed as 36.3" x 13.1" but are 37" in real life) and now my cruise RPM is in the perfect range for me.
A huge plus which I did not anticipate was the vast improvement in ride quality the large increase in sidewall height (AND lower ply count) provided.
It is a night and day difference. So I got a better RPM range (= improved fuel economy, lower cabin noise, longer engine life), much better ride quality, improved ground clearance, improved off-road performance (single tracking, larger tire diameter) and of course the all important 'Expo Look'.
The down side is the Faulken are rated at 3525 lbs so my Fuso has a 'de-rated' GVW, but I run below max GVW so not an issue for me.
A thing to remember for RPM is that our pre-2005 Fusos have 5.715 diffs, while 2005 and later have 4.875 diffs (and 72 lb-ft more of torque)

 

[scubagai]

I also changed to 16 inch rims and running hankook mt 285/75 16. These tires(size at least) are offered everywhere in the North, Central and South America.

 

[canter tourer]

I went with 325/80-16 Faulken Wildpeak A/Ts (listed as 36.3" x 13.1" but are 37" in real life) and now my cruise RPM is in the perfect range for me.

What size rims did you fit?

 

[mog]

What size rims did you fit?

8"x16"

 

[whatcharterboat]

Sorry for the delay. These two vids show a Global Warrior and a Isuzu fire truck both running Toyo 285/70r/19.5" tyres with low pressures. The Global Warrior is running the M608z pattern. The fire truck is running a conventional highway pattern. The fire truck is very heavy as it has 2 ton of water on board along with all the pump gear. Needless to say, the dune is much steeper than it looks and the sand was extremely dry.

[video]http://r7---sn-o097zuer.googlevideo.com/videoplayback?id=a01ecd1de6fbff52&itag=18&source=picasa&ip=101.168.255.224&ipbits=0&expire=1409145835&sparams=expire,id,ip,ipbits,itag,source&signature=1C9EE48476D0EB6AE412DC9B4A880ED8CF57589A .6787CD77DD16B6150C9CA7AF623E502B889BB3B0&key=cms1&redirect_counter=1&req_id=8f97c1b5eafc1397&cms_redirect=yes&mm=26&ms=tsu&mt=1406553804&mv=m&mws=yes[/video]

[video]http://r3---sn-ntq7ened.googlevideo.com/videoplayback?id=62b5fa433b5c5129&itag=18&source=picasa&ip=101.168.255.224&ipbits=0&expire=1409145984&sparams=expire,id,ip,ipbits,itag,source&signature=182B5A80F30F299E53CE69189708DA8B22AF5CEF .03F9A6324D7FB9E8E1295FBF4425AECEA731CEAC&key=cms1&cms_redirect=yes&mm=30&ms=nxu&mt=1406553973&mv=m&mws=yes[/video]

 

[DiploStrat]

Might something like this compensate for the lack of a safety bead on 19.5 rims? Sadly, they do not appear to be available for 19.5 rims yet.

http://www.coyoteents.com/beadlocks-how-they-work.html

 

[westyss]

I know its common to de-rate the GVW but to me it seems counter productive in a way. I went with the FG because if I needed to carry up to GVW I would not have a problem being over gross so could take whatever I felt I wanted or needed with me, and it appears that I will take quite a bit of extra gear with me when I do go on longer trips.
That being said, I am pretty sure that there are many trucks out there operating over gross just simply due to one wanting to take all of their stuff with them, so why lose the ability to do so?

I do not have the self control to leave that one item at home (besides my wife is a collector of ALL things) so I simply take it with me.

Edit: Just to be clear, I am not loading over gross but I have lots of available load carrying ability before reaching gross.

 

[GR8ADV]

ok this was pretty quick and dirty. Just went and measured one of our f650's loaded with goodyear 265/70 19.5's . 100 psi vs 35 psi
.
100 psi patch roughly 8.5x8.5 = 72 sq inches
35 psi patch roughly 12x10= 125 sq inches to outside of buldge
An increase of 74%
.
For comparison I measured a toyo 265/70 17 inch 70 series tire on a pick up.
32 psi patch roughly 9x10= 90 sq inches
20 psi patch roughly 12x12.5 147 Sq inches to outside of buldge
an increase of 63%
.
The 17 inch tire expanded roughly the same amount in both directions.
The 19.5 expanded proportionally much more longitudinally as expected.
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hadn't thought of this.
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For 4-19.5 tires, the total air'd down wheel patch on the sand would be 4x125= 500 square inches
.
For 6-16 or 17 inch duallys, the total air'd down wheel patch size is roughly 6x147= 882 square inches.
.
I know there may be some limitations and efficiencies here with the Duallys, but 880/500 = 76% increase.
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it would take 7 single 19.5's air'd down to equal the patch size of the dually set up.
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6-17 inch rims NOT air'd down = a patch of 540 Square inches which is about 10% greater than the 19.5's AFTER being air'd down.

 

[westyss]

hadn't thought of this.
.
For 4-19.5 tires, the total air'd down wheel patch on the sand would be 4x125= 500 square inches
.
For 6-16 or 17 inch duallys, the total air'd down wheel patch size is roughly 6x147= 882 square inches.
.
I know there may be some limitations and efficiencies here with the Duallys, but 880/500 = 76% increase.
.
it would take 7 single 19.5's air'd down to equal the patch size of the dually set up.
.
6-17 inch rims NOT air'd down = a patch of 540 Square inches which is about 10% greater than the 19.5's AFTER being air'd down.

Thats like a politician crunching numbers to make something look better, how about that one extra dually wheel is creating 76% more drag in the sand.

 

[whatcharterboat]

Thats like a politician crunching numbers to make something look better, how about that one extra dually wheel is creating 76% more drag in the sand.

Actually Yves, it is worse than that. With a SRW , the front wheels plough a set of tracks and the rear wheels follow happily in the same track. With DRW the front wheels plough a set of tracks and the 4 x rear wheels will each plough a track on either side of the front tracks. So instead of 2 tracks there are a messy 6, given that the front run a line close to the gap in the rear duals........................and as you say, the extra drag requires much more power and therefore increased fuel consumption, higher engine temps, etc.

Re: the DRW having more overall flotation. Very good point and true BUT.........with DRW in sand, the front OEM tyres have very little flotation so they knife in deep....then the rear axle which has an abundance of (IMO too much) flotation will not give enough drive so will spin and bog down. Its just a lose, lose situation.....especially the way many expedition trucks are setup with a more even front/rear loading.

Yves, did you like the video?

Regards John.

 

[GR8ADV]

Thats like a politician crunching numbers to make something look better, how about that one extra dually wheel is creating 76% more drag in the sand.

.
76% increase in resistance. I HIGHLY doubt that, but what do I know. Any idea where that number came from?? Are you referring to the added resistance of the rears riding outside of the track of the fronts? If so, that is real, but I really do not think it will be anywhere near 76%. BTW this benefit ONLY exists when if are driving in a perfectly straight line. Also if you are driving in any sort of track made by others it is further greatly reduced.
.
I am not trying to justify anything, I am just trying to look at it objectively without the green colored glasses of spending 5k that I have to justify. Or trying to meet a sales quota. Actually, I am trying to justify getting them, I want them to be awesome cus they look freaking cool and the dually's look lame IMHO.
.
Ok extra drag being out of the track, yup its there, that is why I couched the results with "limitations and efficiencies", however those inefficiencies will likely be considerably less than a 70+% gain in foot print and floatation that is gained and again only there when you are in a straight line. There WILL be additional rolling resistance of the duallys due to having more tires and thus more rubber on the ground, as well as additional resistance of the larger patch. But by definition, that is what we are trying to do with airing down, so we have to accept that knowing it is insignificant compared to the float aspect of the distributed load.

This does not take into account the benefits of wear of the 19.5 on the highway or the gearing. I am strictly looking for ride quality on the highway and off road traction in the sand.

YMMV

 

[EarthCruiser]

Just for fun see how far one can deflate the duals before the start to "kiss" under flex.

 

[GR8ADV]

Just for fun see how far one can deflate the duals before the start to "kiss" under flex.

As far as sand goes closing the gap on the duals with a kiss is likely beneficial. As far as the rubbing 'issue' Both wheels turn at the same time so rubbing is not a big issue. Vibration and constant flexing at higher speeds would be problematic. Although I don't have any facts on this I expect that at sand speeds this will likely not an issue on sand. But that is just an opinion. I would not want to do this at 50 mph, although there is plenty of evidence from people have driven thousands of mikes with no problem.

I am amazed at the amount if mis information and shear speculation that abounds on these threads. Kind of reminds me of how the concept of removing the tailgate on a pickup was suppose to increase mileage.

I am at this point looking at practical issues based on the facts of physics and mathematics. Not trying to convince or persuade anyone. I would just like to figure it out. The engineer in e has an inquisitive mind.