Decision Time - Single Rear Tires vs Dual on Ambulance

[Bikersmurf]

On mine I kept the dual axle as it is larger than the SRW axle and run single wheels on it. I do have a 2" spacer to push the wheel out. It's more for look and I'm considering taking it out as it will track better in line with the front.

My tires are rated at close to 3700lbs, same for rims so I'm good there.

Some rims offer dual wheel pattern (170 & 6.5) which comes handy!

With duallies you'll be limited with tire size. And I'm not a fan of duallies in the snow.

My ambo is 11,000lbs and feels very planted on curvy roads, no issues there.

So I'd fix your rear locker and keep that axle. Mount single 35's and if you're not happy you could always go back but I doubt you will. Plus, converting the front to dually style won't be that fun, keep it SRW





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Hey guys, I've been unearthing the internet for this ambo question with no luck so I'll ask it here since it's related. On an E-Series regular ambo (158") chassis with ujoint 4x4 kit, I want to move to SRW (no super singles). Do most folks that do this put the Dana 60 up front and leave the stock dually axle (FF Dana 60/70) in the rear and run regular wheels? Will the rear wheels be sucked way inboard of the edge of the box with this conif? Would swapping to a Sterling 10.5" in the back help at all with this and has anyone done that?

If you look at Abitibi’s post also quoted in this message, he was running 2” spacers on his dually axle with single rims, but is considering removing the spacer to make his track with closer to the Front axle’s.

Dual wheels have the mounting surface of their wheel about an inch outside of the wheel. If you replaced them with singles with zero offset, the centre of the wheel would be in the centre of where the Dual wheels would have been.

As mentioned above @ujoint lives and breaths this every day in his shop.

 

[Abitibi]

I can confirm that I removed the spacers somewhere on the side of the highway while on a roadtrip in Wyoming... that was after I saw my rear wheel passing me while I quickly pulled over! I was extremely lucky my wheel didn't hit anyone! I managed to recover it, put it back with 1/2 the studs missing and crawled for 5 miles to the next exit where I found a tire shop. I bought some cheap rims, swapped the tires on them and continued on my trip. Fricking scary experience! Same thing happened to my buddy with same setup, but he was going slower and wheel didn't come off but was wobbly as hell and also shredded a bunch of studs.

What I did is bought proper offset rims to fit my rear dually hubs and machined my front disc to accept the same bolt pattern. Now I can rotate my rims without issues and so much safer! Truck tracks great, looks good and no complaints at all.

 

[Ozarker]

To me, there are only a few issues running duals, 1. rocks between tires, 2. inner tire changes being a pain, 3. mpg, 4. cost of replacing tires. #1 isn't a big deal if you know when to pay attention.

Advantage is load capacity, traction and stability, which, as designed for that vehicle, is the best way to go. I like using things as they were designed to be used, any modification interferes with reliability as designed. FWIW!

 

[Peter_n_Margaret]

One incontrovertible advantage of singles is the ability to deflate to 25-33% of road pressure. Certain single wheels can also accommodate internal beadlocks.

Or more.
My philosophy is that if you can not drive up the dune or through the soft sand (or mud), let some more air out. There is no minimum limit.
305/70R19.5 Michelin XDE2s, 2.8T on the front axle and 3.6T on the rear axle. No bead locks.
A dune on a bypass track on the Canning Stock Route. 4th attempt, more air out after each failure.
The difference between the right air and 3psi too much is whether you get up the dune, or not.
This is attempt #4.
With the appropriate air we simply walk up the dune. No screaming engine and no spinning wheels and no risk of pulling a tyre off a rim.


The normal highway pressures are 45psi in the front, 65psi in the rear, cold. These are 14psi and 22 psi HOT.
"Normal" pressures on the Canning were 20psi and 30psi cold and speeds of 20-30kph.
Cheers,
Peter
OKA196 motorhome

 

[keane]

Im having this same debate for my ambo now. Im still 2wd and need new tires in the spring. Currently running 265/75r16 tires on the dually set up. But have been thinking of going to 285/75r16 on single wheels. I have a set of new single wheel front hubs that I can swap to in the front and have some stock F-350 rims. Lots of the 4wd swapped ambo go to srw so why not on a 2wd? Another reason is so I can air down and back up easily. I do lots of back roads and gravel and airing down would be so nice to do. I have a couple months to make up my mind.

On a side question, any one know of a decent system for airing down and up dual rear wheels that doesn't have a stupid price attached.

 

[iggi]

I still haven't done my 4x4 conversion but so far I've decided to stick with the dually setup. There are a couple folks in the FB group that have switched back citing stability issues. As I'm not doing any serious 4x4 trails but do drive fast on windy Albertan highways there seem to be more possible drawbacks for my use than benefits.

I moved up to 235/85R16's as that was the biggest that would fit without a lift or fender trimming. 285's would likely have been my choice if I'd done the lift already. That being said, I'm not certain I would be happy with bigger tires and the factory 4.10 gearing. There are folks in here and in the FB group that run 35's and 4.10's but with the 6.0 and the 5R100 trans I suspect my fuel economy would suffer due to the reduced time spent in Overdrive.

..and yes, I really am hoping to paint or Linex it this summer.

 

[camperulance]

I can confirm that I removed the spacers somewhere on the side of the highway while on a roadtrip in Wyoming... that was after I saw my rear wheel passing me while I quickly pulled over! I was extremely lucky my wheel didn't hit anyone! I managed to recover it, put it back with 1/2 the studs missing and crawled for 5 miles to the next exit where I found a tire shop. I bought some cheap rims, swapped the tires on them and continued on my trip. Fricking scary experience! Same thing happened to my buddy with same setup, but he was going slower and wheel didn't come off but was wobbly as hell and also shredded a bunch of studs.

What I did is bought proper offset rims to fit my rear dually hubs and machined my front disc to accept the same bolt pattern. Now I can rotate my rims without issues and so much safer! Truck tracks great, looks good and no complaints at all.

This looks great! What's the tire/wheel size here?Did you have to have the wheels custom made or is that something available off the shelf with that offset?

 

[Abitibi]

This looks great! What's the tire/wheel size here?Did you have to have the wheels custom made or is that something available off the shelf with that offset?

Rims were available off the shelf. Since I have the Dana Super 60 (with larger rotors) I had to go with 18" Rims but I prefer smaller Rims if it's an option. Tires if I recall are 325/65R18 so a bit wider than other 35's.

 

[camperulance]

Rims were available off the shelf. Since I have the Dana Super 60 (with larger rotors) I had to go with 18" Rims but I prefer smaller Rims if it's an option. Tires if I recall are 325/65R18 so a bit wider than other 35's.

Good to know, thanks! I also prefer a smaller wheel. I'm trying to figure out how to someday switch my DRW to SRW with Toyo Open Country M/T 37x13.5R17 tires, but I haven't quite managed to wrap my mind around what wheel/offsets I would need to make this look good and track correctly. I'll almost certainly need custom wheels though.

 

[Abitibi]

Good to know, thanks! I also prefer a smaller wheel. I'm trying to figure out how to someday switch my DRW to SRW with Toyo Open Country M/T 37x13.5R17 tires, but I haven't quite managed to wrap my mind around what wheel/offsets I would need to make this look good and track correctly. I'll almost certainly need custom wheels though.

Find the offset that pushes your rim the furthest out. Not sure if that equals to -18 or so but if you go 0 offset, the rim will be tucked in at the rear and it will look funny.