Dualies to Single
- Thread starter dzzz
- Start date
That sort of weight capacity is difficult to achieve on single rear wheels without going to "tactical" tires on 20 inch rims. Michelin and Continental are your best bets. Unfortunately, today most military tires are hard to find if you're not wearing coffee-stain cammies.
The latest Earthroamer XV-LT is an example. They offer an optional "meaner tire" combination consisting of Continental MPT81 335/80 tires on 20” Hutchinson internal beadlock aluminum wheels, plus a Kelderman air ride suspension. Cost: about $20,000.
It's probably cheaper to go to 22.5 inch rims and heavy truck tires. Lots of choices here. As the tires get taller, you'll definitely need to to re-gear your differentials so you don't reduce power too much. Re-gearing will lower your top speed, but you probably don't want to drive a 20,000 lbs vehicle much over 65 anyway.
One further concern is the rear axle length. Almost all medium trucks are designed with dual rear wheels in mind. They have a shorter rear axle so the extra rear wheels don't stick out so far. If you switch to single rear wheels, the rears don't ride directly in the tracks of the fronts. If you want the tires to line up, you might be tempted to use a spacer to move the rears out a little. This raises problems with increasing the load on the rear axle bearings. So a better solution is a longer rear axle.
Tell us more about your 10-ton off-road vehicle plans!
Chip Haven
The latest Earthroamer XV-LT is an example. They offer an optional "meaner tire" combination consisting of Continental MPT81 335/80 tires on 20” Hutchinson internal beadlock aluminum wheels, plus a Kelderman air ride suspension. Cost: about $20,000.
It's probably cheaper to go to 22.5 inch rims and heavy truck tires. Lots of choices here. As the tires get taller, you'll definitely need to to re-gear your differentials so you don't reduce power too much. Re-gearing will lower your top speed, but you probably don't want to drive a 20,000 lbs vehicle much over 65 anyway.
One further concern is the rear axle length. Almost all medium trucks are designed with dual rear wheels in mind. They have a shorter rear axle so the extra rear wheels don't stick out so far. If you switch to single rear wheels, the rears don't ride directly in the tracks of the fronts. If you want the tires to line up, you might be tempted to use a spacer to move the rears out a little. This raises problems with increasing the load on the rear axle bearings. So a better solution is a longer rear axle.
Tell us more about your 10-ton off-road vehicle plans!
Chip Haven
dzzz
™
Thanks chip, The logical thing for me to buy would be a large truck camper. But I have to admit I hate the look. I also like to do my own designs. As soon as I buy off the shelf I want to change everything.
As far as GVW, I'm trying to figure out what's realistic. My max vehicle length is 22 feet with a space for two. One of the two being female.
We have quite a few big custom box truck builders in my area. I'm talking to them about building the camper shell. I don't want a shell that sits on a flat bed. This puts the floor too high. I am thinking about a pop up that is usable with the roof down. Or at least "sleepable" with the roof down. My issue here is AC and solar. The roof needs to be liftable with this equipment, as well as strong enough to hold a good amount of snow.
I do a lot of photography and videography in the fall. We snow on leaves really pulls the branches down. A lower roof plus rub guards to push branches away is beneficial. My current ruck doesn't have extensive brush guards and has fine scratches everywhere.
My concern with duallies is that I do accidentally end up in twisted positions. I do end up backing in ditches. That's not likely to change.
As far as the camper - Espar everything and a cassette toliet. Fresh water in the camper, grey water below. One propane tank. Generator is undecided. The only generators I like are Honda. I would be willing to use these portables, but then I'm carrying gas. I did find a guy that does propane conversion on honda. But as I plan to have at least 80 gallons diesel, that really should be my fuel source. A clean design would be just diesel and electrical power.
So, what do I give up going dually?
As far as GVW, I'm trying to figure out what's realistic. My max vehicle length is 22 feet with a space for two. One of the two being female.
We have quite a few big custom box truck builders in my area. I'm talking to them about building the camper shell. I don't want a shell that sits on a flat bed. This puts the floor too high. I am thinking about a pop up that is usable with the roof down. Or at least "sleepable" with the roof down. My issue here is AC and solar. The roof needs to be liftable with this equipment, as well as strong enough to hold a good amount of snow.
I do a lot of photography and videography in the fall. We snow on leaves really pulls the branches down. A lower roof plus rub guards to push branches away is beneficial. My current ruck doesn't have extensive brush guards and has fine scratches everywhere.
My concern with duallies is that I do accidentally end up in twisted positions. I do end up backing in ditches. That's not likely to change.
As far as the camper - Espar everything and a cassette toliet. Fresh water in the camper, grey water below. One propane tank. Generator is undecided. The only generators I like are Honda. I would be willing to use these portables, but then I'm carrying gas. I did find a guy that does propane conversion on honda. But as I plan to have at least 80 gallons diesel, that really should be my fuel source. A clean design would be just diesel and electrical power.
So, what do I give up going dually?
charlieaarons
Explorer
If you adjust gear ratios proportional to tire size increase, speed and torque will stay exactly the same.
Sometimes, but not always, you can luck out by using a wheel with a carefully calculated offset "out" in the rear and "in" in the front and track will be close to equal (reversible wheels, hub-centric mounting).
Sometimes the front track matches the inside rear, sometimes the outside rear, sometimes halfway in between. Get out a pencil and a piece of paper and a tape measure. It is critical to know which applies to your chassis when designing singles.
I highly recommend avoiding spacers, they can be very dangerous, more so on a heavy vehicle. This is controversial.
It is not the worst thing to have 2 different offset wheels: zero offset for the rear, and whatever is best for the front; usually maximum offset that won't rub on turns. Having an emergency incorrect offset wheel in the rear (a flipped front spare) won't stop you in your tracks. It's good to carry a 2nd unmounted spare, perhaps on top of the camper or cab.
If someone is really interested, I can e-mail a 13 page pdf "Michelin truck tire characteristics ". It's VERY comprehensive and a large source of my information.
Charlie
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mcgovski
Adventurer
increasing your tire weight rating does not increase your payload as I understand it. It only increases your tires ability to deal with the weight...It is a good thing to improve at such weight as the tires could be seen as the weakest link...that being said, i dont think tires will increase your trucks payload
Chris
Chris
re: truck payload
You have to start with a vehicle that has an adequate GVWR for your application. Adding different rear wheels and tires does not change the truck chassis GVRW.
For example, the Ford F550 can be ordered with 19,500 lb GVWR, 4x4, diesel engine and dual rear wheels. The GMC C5500 4x4 is similar. Then you have to find the right wheels and tires (and maybe a different rear axle) to convert to "super singles."
Chip Haven
You have to start with a vehicle that has an adequate GVWR for your application. Adding different rear wheels and tires does not change the truck chassis GVRW.
For example, the Ford F550 can be ordered with 19,500 lb GVWR, 4x4, diesel engine and dual rear wheels. The GMC C5500 4x4 is similar. Then you have to find the right wheels and tires (and maybe a different rear axle) to convert to "super singles."
Chip Haven
I've decided to go with a flatbed and pull a trailer rather than have a chassis mount or slide in camper so I don't need the weight carrying capacity I anticipated needing 9 years ago when I bought it. Here are my plans. http://www.expeditionportal.com/forum/showthread.php?t=25237
http://www.expeditionportal.com/forum/showthread.php?t=24454
Mine was a regular dually pickup. I followed this excellent post by edcasey. http://www.expeditionportal.com/forum/showthread.php?t=20727 go to post #4.
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charlieaarons
Explorer
If the vehicle is a F350 dually with a "regular" front Dana 60 and a spacer it is, as referred to above, easy; simply remove the front spacer and use normal wheels.
However, the newer F550s use the Dana "super 60" front axle. There's a good article in the recent Petersen's 4 Wheel & Offroad June 09. The Super 60 has a different, wider hub. However, it can be replaced using a F350 hub and unit bearing. But that will cause the front to be 8 bolt instead of 10 bolt. Perhaps Dynatrac can be of some help in this? Call them and describe the issue, they may be able to supply or make the necessary part, to use low or zero offset wheels in order to run 35-42" singles. Sizes to look at: 285/70R19.5, 305/70R19.5, 335/80R20 (Michelin XZL 141K, Continental MPT81 147K), 13/80R20 (Michelin XZZ, 8000 lb, 41.2", undoubtedly unobtainium, obsolete), Michelin 10.00R20 XZY-2, 147K.
Note I am not listing any 22.5s. As I have stated before, the only functional (non-cosmetic) reason to run "super" singles is offroad ability. 22.5s in the sizes appropriate for a F550 have sidewalls too short to be useful in this area. For example, a 255/70R22.5 has only a 7" sidewall and a 60 sq in footprint. Even a 305/70R22.5 has a 8.4" sidewall and at most 84 sq in footprint. A 335/80R20 has a 10.3" sidewall and a 109 sq in footprint. You want the smallest rim so you get the most "squash" at lower psi.
Charlie
However, the newer F550s use the Dana "super 60" front axle. There's a good article in the recent Petersen's 4 Wheel & Offroad June 09. The Super 60 has a different, wider hub. However, it can be replaced using a F350 hub and unit bearing. But that will cause the front to be 8 bolt instead of 10 bolt. Perhaps Dynatrac can be of some help in this? Call them and describe the issue, they may be able to supply or make the necessary part, to use low or zero offset wheels in order to run 35-42" singles. Sizes to look at: 285/70R19.5, 305/70R19.5, 335/80R20 (Michelin XZL 141K, Continental MPT81 147K), 13/80R20 (Michelin XZZ, 8000 lb, 41.2", undoubtedly unobtainium, obsolete), Michelin 10.00R20 XZY-2, 147K.
Note I am not listing any 22.5s. As I have stated before, the only functional (non-cosmetic) reason to run "super" singles is offroad ability. 22.5s in the sizes appropriate for a F550 have sidewalls too short to be useful in this area. For example, a 255/70R22.5 has only a 7" sidewall and a 60 sq in footprint. Even a 305/70R22.5 has a 8.4" sidewall and at most 84 sq in footprint. A 335/80R20 has a 10.3" sidewall and a 109 sq in footprint. You want the smallest rim so you get the most "squash" at lower psi.
Charlie
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