[Sudarshan]

I dont know where to post this for discussion , but at least let me post here than not at all.

Recently came across a Military Jeep's picture on the FB . It looked like some kind of trial .

Following things came to my mind .

# Is it really possible to do it on any MM Jeep , without overloading its FFRA Hub ( bearings ) or SFRA setup ?

# It will certainly demand stronger wheel mounting studs .

# Looks convenient , drive without additional tires in normal conditions & add them when needed . Advantage reduced friction /drag , will save tire wear & fuel .

# Down side is carrying them around or storage at garage .

# Can a smaller wheel be attached ? ( instead of regular one ) As it will not touch the surface when running on hard ground ( leveled ) but will provide service when the larger wheel sinks .

Here to share



Sudarshan

[SPIKE ARRESTOR]

Interesting, may be UBS Sir may have something to share on these.

On a lighter note, why need 4 extra tires, when 4 tractor tires come in "equivalent" sizes to these?

Spike

[Sudarshan]

Another pic I found regarding this .

Here , Oct 1952 , Motor trend magazine .



I see Number of possibilities & combinations regarding this .

About tires of equivalent size ? Yes there are , but they keep generating unnecessary traction even on non slippery surfaces , thereby increasing loads on engine & thus probably cause overheating ( ? )


Sudarshan

Edit ; also here http://www.thecj2apage.com/forums/du...opic24635.html

[Frankenstein]

Sudharshan bhai , what is the point of this?
I too thought of double tires , even tried to find out those small mahindra or tata truck rear axles which use 4 tires.

Even if we use 4 tires say at the rear for example , we can use ndms or similar narrow tire and not a mud terrain .

Even if you take the width of two 7.50x16 tires it is 365mm. Most of todays mud terrain tires are between 265mm and 315mm. How much difference would it make , what about the extra width , how will you tackle water or mud from throwing inside your Jeep?, what about the strain on the steering, with the army tires or mud terrain tires itself the steering struggles and barely holds, what will happen with all the extra load on the steering and suspension ?

This idea would have made sense in the old days where there were no wide tires , or atleast if the vehicle is carrying load .

Today we have M/T tires and what is the load we carry on a offroad Jeep , its NIL.

[Sudarshan]

Originally Posted by Frankenstein

even tried to find out those small mahindra or tata truck rear axles which use 4 tires.

That would be an excellent thing to be used at the rear . Provided front diff ratio is matching . Thanks for this Idea .

Even if we use 4 tires say at the rear for example , we can use ndms or similar narrow tire and not a mud terrain .

Exactly, my further quotes will explain why .

what I am trying to suggest is not only the extra width available for traction, but removing the added tire when running on hard surfaces where the extra width ( read traction ) is not needed , thus reducing the unnecessary friction . Remember 80% running of a 4x4 is done in non 4x4 conditions .

Originally Posted by Sudarshan

About tires of equivalent size ? Yes there are , but they keep generating unnecessary traction even on non slippery surfaces , thereby increasing loads on engine & thus probably cause overheating ( ? )

Originally Posted by Sudarshan

# Looks convenient , drive without additional tires in normal conditions & add them when needed . Advantage reduced friction /drag , will save tire wear & fuel .

# Can a smaller wheel be attached ? ( instead of regular one ) As it will not touch the surface when running on hard ground ( leveled ) but will provide service when the larger wheel sinks .

what about the extra width , how will you tackle water or mud from throwing inside your Jeep?,

Frankie ; days of open Jeeps seem to have gone, order of the day is AC cabin

what about the strain on the steering, with the army tires or mud terrain tires itself the steering struggles and barely holds, what will happen with all the extra load on the steering and suspension ?

Oh yes you are right here, but it can only be used at rear.

I will post some pics I have & my own research ( big word it is ) on this .

Mean while keep it in thinking, & sharing thoughts

Sudarshan

[Frankenstein]

Originally Posted by Sudarshan

That would be an excellent thing to be used at the rear . Provided front diff ratio is matching . Thanks for this Idea .



Exactly, my further quotes will explain why .

what I am trying to suggest is not only the extra width available for traction, but removing the added tire when running on hard surfaces where the extra width ( read traction ) is not needed , thus reducing the unnecessary friction . Remember 80% running of a 4x4 is done in non 4x4 conditions .







Frankie ; days of open Jeeps seem to have gone, order of the day is AC cabin



Oh yes you are right here, but it can only be used at rear.

I will post some pics I have & my own research ( big word it is ) on this .

Mean while keep it in thinking, & sharing thoughts

Sudarshan

Only rear can be a good idea or or, let the inside main tire be a bigger 7.50x16 and the outer be smaller 6.00x16 tractor tire so that it engages when the ground is loose.

I saw tandem tyres on a small mahindra garbage truck .

Open Jeeps are going to make a comeback very soon with mind blowing performance , Open is a Jeep and Jeep is open , rest are cars

Sudharshan Bhai even in todays OTRS open short chassis Jeeps with DIESEL engines and proper tires is still way ahead of the front bogging weak fake Jeep with no life low down.

In technical terms, weak suspension , no low end power and needs to be driven very unlike a Jeep .

[ringoism]

Forget for a moment any mechanical limitations: Generally, I just don't think this sort of thing is going to work well off-road, except maybe on certain kinds of surfaces (maybe sand or very loose, deep dirt?) where more "flotation" is desirable, to avoid digging in / getting bogged down. For more typical and varied trail / wasteland use, beyond simply not being able to "use" the tires' profiles very well (tire can not deflect as a single unit to create a flat contact patch over an uneven surface, nor can it easily dig down to firmer earth below whatever surface slop exists), there are issues of mud / stones getting jammed between the tires. And I don't think you'd be able to deflate them much to improve traction on certain surfaces, since the bulging sidewalls would rub against each other and destroy all eight tires pretty quickly.

In the U.S. there are lots of "dually" pickups (rear axle only), but these are used to increase load capacity for towing / hauling (and occasionally for style, due to associations with heavy trucks) - But as common as they are, and despite the fact that a number of them are 4x4's, I have NEVER seen or heard of one doing serious off-road duty. Nor, might I add, have I ever seen one being used for a snow-plowing rig. In fact, I think the only reason a lot of them are ordered as 4x4's is because traction on a 2wd dually is pretty bad - and a lot of people who haul horse trailers, etc, have to drive out across wet / occasionally muddy fields where events are staged, etc.

Here in India, I've watched numerous "tandem" equipped trucks (including 4x4 tippers, etc) struggling in mud or snow that didn't look bad at all, not seeming able to create a real contact patch despite all that rubber, and with whatever loose stuff (snow/mud) jamming up between the treads actually PREVENTING either tire from settling down and gripping anything. I have also noted that the more off-road oriented 4x4 Army trucks and recovery vehicles NEVER use dual wheel setups on either axle.

I'm sure that steering effort would be ridiculous, too.

Just a bad idea all-around. If anyone feels inclined to try it and prove me wrong, I'll be happy - if it works for your purposes, great; If not, I could probably buy the four extra tires off you later (at a steep discount, of course) okay?

On the positive side:

1) You could potentially run with four punctures simultaneously! Might make good getaway vehicle for bank robbers???

2) With all that air in eight tires on a lightweight SWB early CJ, you might be able to float across the surface of water bodies instead of having to drive through them! So you can throw away your snorkel in lieu of a boat propeller on your PTO! :-)

I'm indeed pretty curious to know the source of that picture... but would be willing to bet (if I were a betting man) that it was in service somewhere in a sandy desert, or maybe a place where there was an encrusted surface that the vehicle was intended to drive over rather than break through. I think these are the only sorts of places that something like this might be an advantage.

Regards,
Erik

[Sudarshan]

Originally Posted by ringoism

there are issues of mud / stones getting jammed between the tires.

Agree here

And I don't think you'd be able to deflate them much to improve traction on certain surfaces, since the bulging sidewalls would rub against each other and destroy all eight tires pretty quickly.

Disagree with deflating , agree with sidewall rubbing & having a stone jammed between them in the act itself = bad

In the U.S. there are lots of "dually" pickups (rear axle only), but these are used to increase load capacity for towing / hauling (and occasionally for style, due to associations with heavy trucks)

Style is good for health

I have also noted that the more off-road oriented 4x4 Army trucks and recovery vehicles NEVER use dual wheel setups on either axle.

Disagree , slight OT but the old TMB recovery trucks for Indian Army were such . Recovery vehicles is a mixed area .

I'm sure that steering effort would be ridiculous, too.

Agree , certainly . That would be a worst steering .

Just a bad idea all-around. If anyone feels inclined to try it and prove me wrong, I'll be happy - if it works for your purposes, great; If not, I could probably buy the four extra tires off you later (at a steep discount, of course) okay?

AAWWAA -- not too bad idea sirji

2) With all that air in eight tires on a lightweight SWB early CJ, you might be able to float across the surface of water bodies instead of having to drive through them! So you can throw away your snorkel in lieu of a boat propeller on your PTO! :-)

YES flotation, yes thats the point .

Please do think about the point where I mentioned using a larger & smaller tyre in tandem .

Thanks for detailed sharing

Sudarshan

[ringoism]

Originally Posted by Sudarshan

Disagree , slight OT but the old TMB recovery trucks for Indian Army were such . Recovery vehicles is a mixed area .

YES flotation, yes thats the point .

Please do think about the point where I mentioned using a larger & smaller tyre in tandem .

I was totally ignorant of what a TMB (incl. recovery vehicle variant) was till checking the Classic Commercial Vehicles thread, where I found photos of a nice ex-army RV unit, and realized I'd seen them in various parts of India before. Certainly nice for their time, but in a whole different (and lesser) league from the current hard-core recovery vehicles being exclusively used by GREF / BRO between Manali and Rohtang Pass, at least (with mud/snow/ice/landslides, some of the most nasty terrain at times), which design-wise are more reminiscent of Unimogs, etc. When the TMB's were around, the more massive tires these use were presumably not available, and dually setups helped fulfill the GVW requirements for towing.

As far as the smaller/larger tandem tires - interesting idea which might work on certain surfaces... maybe really nasty, deep mud where the fact of different rolling circumferences wouldn't matter as much??? But I dunno... this difference is going to require one or both to slip to make up that difference, and might actually promote breaking of traction rather than any increase.

I think someone should try it (but not me!)
]
-Erik

[Sudarshan]

Something I found on FB

Thanks to Mallikarjun Sajjanshetty ,my FB friend.




Sudarshan

[Parm]

Did someone said tires?

Well he is something making Punjabis going crazy these days. I'm sure Jeeps will soon replace Tractors in Punjab!

I call this Tractor Head (on the lines of Petrol heads and Diesel heads)!

[cr4nkshaft]

Originally Posted by Parm

Did someone said tires?

Well he is something making Punjabis going crazy these days. I'm sure Jeeps will soon replace Tractors in Punjab!

I call this Tractor Head (on the lines of Petrol heads and Diesel heads)!

haha! now just put the chassis a little higher and you've got a desi monster truck!!

[commander]

Originally Posted by ringoism

For more typical and varied trail / wasteland use, beyond simply not being able to "use" the tires' profiles very well (tire can not deflect as a single unit to create a flat contact patch over an uneven surface, nor can it easily dig down to firmer earth below whatever surface slop exists), there are issues of mud / stones getting jammed between the tires.

Regards,
Erik

I have noticed similar experiences on trucks (Ashok Leyland Taurus 2516 multi axle trucks - borewell rigs *30/33 tonnes). When stuck on wet areas of agricultural land, the mud tends to end up between the sidewalls thereby engulfing both tires causing loss of traction. The more progress you make the more mud enters making it thicker inside. Requires sufficient manpower and crow bars to pick them out and constant cleaning of the tires. And they come with a double crown which can be activated by a switch to send power to second crown. What generally helps are the hydraulic jockeys that are used to lift the rigs and place rocks or rods under.

Sudarshan sir, how about a 6*6 with a similar double crown set up.? Wouldn't that be super awesome

Regards
Barani

[Sudarshan]

Someone in India has actually done it .

Picture credit, again to Mallikarjun Sajjanshetty (these pics are also from his FB page ), Thanks to him for that.







Sudarshan