Simple question for SRW owners...

Hodor

Active member
Tried searching and the amount of information available is too much to sift through for this simple of a question -

Do the available SRW conversions increase the track width between the tires on the rear axle?

Im measuring from inside-of-tire on both sides, and wondering what the new numbers would be on a single wheel setup.

Thanks yall!
 

SkiFreak

Crazy Person
So the dually rear wheels have the same inside width as the single rear wheels?
No.
It is the inside wheels that get removed when you go to singles, so there is significantly more space between the tyres at the rear when you run singles.
The offests on the singles is slightly different from the OEM rims too, which allows the track on the front and back to be the same.

To add to this a bit...
When running singles, the brake drums at the rear are fully exposed, unlike when running duals, where the brake drums are fully covered by the rims.
 
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Ultimark

Active member
Firstly, what is an SRW? Is it a Mitsubishi or a Fuso vehicle?

Regardless, here are a some of pictures of the rear wheels of our Isuzu 75-155 4x4 after conversion to super single wheels. You can see the rear brake drum on the inside quite easily. The other picture shows the outside and how they look on the rear axle.

As for track width; yesterday I answered that in another thread, so I'll use the same picture. Outside tyre to outside tyre measurement is 2040mm actual tyre tread width measured on a spare tyre, is approximately 285mm so 2040mm minus 570mm for the tyre tread on the ground, will leave you with an inner measurement of 1470mm inside tyre to inside tyre. Please bear in mind these are the measurements on our Isuzu, they will be different on other vehicles and obviously dependent upon axle size.

Tyre_Track_001_Tyre_Track_003_IMG_20211223_120603.jpg

Wheel_Inside_Rear_IMG_20211224_090007.jpg


Wheel_Outside_Rear_IMG_20211224_090102.jpg
 

billiebob

Well-known member
Do the available SRW conversions increase the track width between the tires on the rear axle?
yes, rear track increases.... track is the measure from tire centerline to tire centerline.
Rear track with duals is the measure, from the mating rim surfaces, centerline of the track.

When the front axle width is different than the rear axle width you need rims with different offsets to achieve identical front and rear tracks. The ideal is engineering for a flip flop rim. OR if the rear axle width is narrower than the front axle width you might get lucky when you remove the inside rim but I cannot imagine the stress increase on the rear axle by offsetting the load so dramatically. I guess the fact no overland vehicle carries anywhere near the designed rear axle weight capacity on a Fuso helps reduce some of the stress.

EDIT If you are buying new rims designed to achieve the same track.... that is the well engineered route to go.
I believe the photos above are using rims with much less offset than the stock rear dual rim.

By simply removing the inside rim you are actually doing this...

79039514_2485738101711344_5955381230064107520_n.jpeg

Will I get the same track front and rear???? far too many variables to say yes or no. You need to measure the actual vehicle.
 
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Ultimark

Active member
The wheel conversion kit shown above, is from All Terrain Warriors (ATW) in Australia, we have the 17" steel wheel kit.


If you wish to retain the original load carrying capacity of your light truck, then you will need to have a wheel and tyre kit capable of doing that. ATW have their 19.5" conversion kit, this is their steel wheel kit; there is I believe, an alloy wheel version in the 19.5" size as well. In Australia this allows the manufacturer's Gross Vehicle Mass (GVM) to be retained, other jurisdictions will probably be different.

The 19.5" kit allows for 6000kg on the rear axle, I'm not sure what the rear axle rating is for other vehicles, but the Isuzu rear axle is designed for 6600kg but in reality is limited in the OEM with duals on the rear to 4400kg. The NPS Isuzu front axle is rated to 3100kg and with the GVM being 7500kg that leaves a maximum legal rear axle load of 4400kg. There are many factors when it comes to axle loads, which certainly makes life quite interesting when you are deciding what and how you can achieve your desired outcome within the design parameters of the vehicle's GVM and individual axle load rating in whatever part of the world you are registering it.

 

BigSkyBrad

Active member
I've just gone outside in 3degC and measured the track width of my singles on my Canter. The front track (centre of tyre to centre) is 1725mm and the rear track is 1755mm - this has been achieved with a +90 ET (offset).

I forgot to factor in the 10mm thickness of the mounting plate when I got my rims made, so that's 20mm of the difference I have between front and rear. The other 10mm would be taken care of by making the offset +85 (or +87.5? - I've had a big Xmas roast lunch and can't think straight!) But I've not lost any sleep over 30mm.

I've got about 1.5 inch space between the steering ball joint and my 17.5x6.75 rims (265/70-17.5 tyres) - whether a 17x9 with +90 offset woiuld clear the knuckle I don't know.

From memory, the standard 6-stud Canter offset is +127-129.

People get confused between offset and backspace. Below is offset, both positive(+) and negative(-). Regardless of the width of a rim, the centre is always at the centre.

1640454283101.png

Someone mentioned above that without the inside dual on, the bearing loading would be severely compromised. However the axle is rated to 6000kg, and as the cab-chassis rear axle weight is 1000kg and the permitted payload is 3600kg, the axle will only ever see 4600kg max - plenty of redundancy there.
 
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BigSkyBrad

Active member
(Canter) Was having a re-think there. A 9" rim is 1-1/8" wider from centreline than my 6.75" rim. With a corrected offset from my +90 to +80, a 9" rim should just clear the steering knuckle and allow for a slight rim run-out, and give the desired matching front and rear track width. Anything wider than a 9" rim would be impossible to have both matching track and component clearance.

Don't quote me on any of this, work it out for yourself.
 
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sixbennetts

Adventurer
What's the difference in track width compared to the front if you just remove the 2 inner rear rims/tires?

I'm in the states, and will only be carrying a ton, maybe ton and a half in weight.
 

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