SRW's for FUSO

[whatcharterboat]

I am not sure why you say you can't air these tires down? They can't be aired down as effectively as a 35" tire on a 16" rim but they can be aired down. In sand or rough conditions I air my XDE2+ down to 22-24 psi front and 28-30 psi rears and that makes a for a much improved ride on both sand and rock.

Just to reinforce Yves statement above.

We recently did some training for one of our rural fire services to instruct them on the use of 19.5s in soft sand. Purposely getting bogged, airing down to around 20psi, recovery, etc. .....and then we really, really pushed the trucks hard and fast into sand berms trying to pop a bead. If they were going to pop off at that low PSI then they would have. At 20 psi to 25 psi they bag out well with this size truck and get you just about anywhere you need to go in soft sand.

Some of the commercial beach buses have been running the 19.5"s in preference to the "baggy" 16"s for the last 5 years. Obviously they will not air down as well as a 37" x 16" tyre but the pros have found that the issues of punctures and sidewall damage are all but eliminated with the stronger tyres. This is the scenario I would prefer in an expedition truck in remote country.

 

[GR8ADV]

Just to reinforce Yves statement above.

We recently did some training for one of our rural fire services to instruct them on the use of 19.5s in soft sand. Purposely getting bogged, airing down to around 20psi, recovery, etc. .....and then we really, really pushed the trucks hard and fast into sand berms trying to pop a bead. If they were going to pop off at that low PSI then they would have. At 20 psi to 25 psi they bag out well with this size truck and get you just about anywhere you need to go in soft sand.

Some of the commercial beach buses have been running the 19.5"s in preference to the "baggy" 16"s for the last 5 years. Obviously they will not air down as well as a 37" x 16" tyre but the pros have found that the issues of punctures and sidewall damage are all but eliminated with the stronger tyres. This is the scenario I would prefer in an expedition truck in remote country.

This is contrary to everything I have read. Thx for the real world info. Anyone want to take a pic of their 19.5 at 25 psi❓

 

[whatcharterboat]

This is contrary to everything I have read. Thx for the real world info. Anyone want to take a pic of their 19.5 at 25 psi❓

I have some video of that day I mentioned with the fire trucks and one of our motorhomes going up a steep soft sand dune ....so will try to get link to it .....haven't done that before with video. Will try tonight. That should help to demonstrate what we are talking about here.

 

[pugslyyy]

I have some video of that day I mentioned with the fire trucks and one of our motorhomes going up a steep soft sand dune ....so will try to get link to it .....haven't done that before with video. Will try tonight. That should help to demonstrate what we are talking about here.

That would be great to see!

 

[whatcharterboat]

That would be great to see!

Hi Pugslyyy,

Still trying. I think I have to get it up on youtube or similar first.???? It's not much. Just a couple of quick clips of the trucks charging up a dune but should show enough. I also have photos somewhere of the tyres and tyre tracks at different pressures on the beach.....but look at this>>>>

http://www.allterrainwarriors.com.au/_literature_3753/Tyre_Inflation_Guide

 

[Haf-E]

So the 19.5" tires increase the contact area by 100% (twice as much area) when aired down to 20 PSI. That's a big increase!

 

[GR8ADV]

So the 19.5" tires increase the contact area by 100% (twice as much area) when aired down to 20 PSI. That's a big increase!

Although I don't know this for sure, I do not think the example is using a 19.5 tire.

 

[Amesz00]

Although I don't know this for sure, I do not think the example is using a 19.5 tire.

I think the measurer was using an optimists' measuring tape...
Seriously though, looking at the pics it seems it was measured in the sand, ie not from a hard surface... With the low sidewall profile of the 19.5 I would think the rim would be on the ground long before it reached a 500mm contact patch..
That's around what I got from the 11.00 r16 michelins on my old canter at 13psi (I bogged it in a friends muddy paddock one day..)

 

[westyss]

I think the measurer was using an optimists' measuring tape...
Seriously though, looking at the pics it seems it was measured in the sand, ie not from a hard surface... With the low sidewall profile of the 19.5 I would think the rim would be on the ground long before it reached a 500mm contact patch..
That's around what I got from the 11.00 r16 michelins on my old canter at 13psi (I bogged it in a friends muddy paddock one day..)

I want to say that those numbers are realistic, only John can answer that but those tires as stiff as the side wall is do spread out significantly, I have just spent 3 months in the Baja and we did most of our camping on the beaches and without airing down I was going no where but get the air out and those tires look like they make a contact surface just like the link John posted.

 

[GR8ADV]

Westyss, thanks for the input, and GREAT build thread btw. Can you get a pick of the tires air'd down on pavement?

 

[whatcharterboat]

Although I don't know this for sure, I do not think the example is using a 19.5 tire.

The tyre shown in that link is a Toyo M608z 285/70R/19.5. The weight on the single tyre would be around 1500kg (3300 lb).

Yes the 20psi patch was measured in the sand but so was the 65psi patch. It shows the difference between the two pressures in the same soft ground. We thought that would represent what actually happens on the beach.

Videos still coming.

 

[GR8ADV]

Hi Pugslyyy,

Still trying. I think I have to get it up on youtube or similar first.???? It's not much. Just a couple of quick clips of the trucks charging up a dune but should show enough. I also have photos somewhere of the tyres and tyre tracks at different pressures on the beach.....but look at this>>>>

http://www.allterrainwarriors.com.au/_literature_3753/Tyre_Inflation_Guide

send me the clip and I will load it up or you

 

[whatcharterboat]

send me the clip and I will load it up or you

They are all around 60mb. I've got a friend onto to it today but thanks for the offer.

 

[Amesz00]

The tyre shown in that link is a Toyo M608z 285/70R/19.5. The weight on the single tyre would be around 1500kg (3300 lb).

Yes the 20psi patch was measured in the sand but so was the 65psi patch. It shows the difference between the two pressures in the same soft ground. We thought that would represent what actually happens on the beach.

Videos still coming.

Hi john,
Not trying to be rude, sorry if that's how it comes across..
My problem with that method of measurement is that it depends entirely on the depth and consistency of the sand.. ie the truck could have been driven into windswept talcum powder like beach sand @ 70psi, bogged to the diffs then measure contact patch at over 2ft long... If you get what I mean, I know that's not what happened but its just an over exaggerated Description.. know what you were trying to say though.

 

[GR8ADV]

Hi john,
Not trying to be rude, sorry if that's how it comes across..
My problem with that method of measurement is that it depends entirely on the depth and consistency of the sand.. ie the truck could have been driven into windswept talcum powder like beach sand @ 70psi, bogged to the diffs then measure contact patch at over 2ft long... If you get what I mean, I know that's not what happened but its just an over exaggerated Description.. know what you were trying to say though.

��Yup that is why we need somebody with these babies to give us a pic on the pavement. C'mon people��

Now that I have said that, two people have provided real time input that airing them down works for them.