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# contact area between tire and steel deck of reach Stacker?7

## contact area between tire and steel deck of reach Stacker?

(OP)
The upper deck of our RORO ship will be loaded with containers and for this purpose the reach Stacker will be used to stack containers on the deck.The reach Stacker has a dead weight of 70 tons and a container weight of 45 tons with 4 18.00-25 "air tires for the front wheels and 2 18.00-25" air tires for the rear wheels.
I would like to ask how to determine the contact area and pressure between front wheel and steel deck of reach Stacker?
How to distinguish tire contact AREA from AREA OF LOAD WORK?
Thanks

Hans

1. When calculating the strength of deck and strengthening beam, it is necessary to know the average load of vehicle tire;
2. The average load here is not equal to the axle load divided by the wheel mark of the tire;
4. I don't understand the relationship between "AREA OF LOAD WORK" and" foot print of tire" here

### RE: contact area between tire and steel deck of reach Stacker?

2

If you're not in class I did find this document that may assist you:

https://www.diva-portal.org/smash/get/diva2:612289...

### RE: contact area between tire and steel deck of reach Stacker?

Contrary to what many people think, the average contact patch area is NOT the load divided by the pressure. Nor is the average contact pressure the same as the inflation pressure. If you want to use that as an approximation, be aware that the actual value can be off by a factor of 2!

The way to get the value is to talk to the maker of the equipment - who will in turn get it from the tire manufacturer.

### RE: contact area between tire and steel deck of reach Stacker?

Good pub Tug... I didn't know they had that type of publication.

@CapriRacer... do you have a link that explains that a bit. I've always used that and was not aware it could be off by 2... I've always thought it was a good general guide... I've done many warehouses and runways using that approach.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

### RE: contact area between tire and steel deck of reach Stacker?

Among other things, load / pressure neglects the stiffness of the tire's carcass, which is not negligible for some types of tires.

### RE: contact area between tire and steel deck of reach Stacker?

Adding onto CR & MJ’s comments, off-road tire stiffness varies a lot more than onroad and usually depends on the use case of the equipment, not the type of equipment.

### RE: contact area between tire and steel deck of reach Stacker?

Dik,

I have a webpage that is sort of a proof that the inflation pressure is NOT the average contact patch pressure: Link

The key to the proof is that it's the tire holding up vehicle, not the air. Stiffen the tire and you will get a different contact patch size. Unfortunately, most of a tire's stiffness comes from the inflation pressure, not the sidewall - hence the confusion.

Within tire engineering circles, it is so well understood that even researching technical papers on the subject doesn't yield anything. However, it can be found imbedded in the guts of some papers - hence the reference to a factor of 2!

And lastly: My webpage shows that in 2012, I planned to measure what happens to a tire when it is loaded - even made predictions. I found I couldn't measure things accurately enough using simple tools, so I abandoned the project. I need to update that webpage.

### RE: contact area between tire and steel deck of reach Stacker?

Thanks... bookmarked.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

### RE: contact area between tire and steel deck of reach Stacker?

PCA Pavement for aircraft shows it's the area due to pressure. It may be that aircraft tires do not have the same sidewall stiffness as heavy earthmoving equipment, so the factor may be closer to 1. Thanks

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

### RE: contact area between tire and steel deck of reach Stacker?

I've run across the tire stiffness bit; I once drove for a long time with a rear tire leak and couldn't even tell that the tire was deflated because the sidewalls were pretty stiff and it was a relatively light car.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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### RE: contact area between tire and steel deck of reach Stacker?

Run-flats... the epitome of strong sidewalls and practically no change in contact surface area.

Dan - Owner
http://www.Hi-TecDesigns.com

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