I'm sending this again because the first time has not yet appeared on the list.
Jim Wiehe , VA3JHW
mail to : j.wiehe@sympatico.ca
----- Original Message -----
From: "James Wiehe" <j.wiehe@sympatico.ca>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>; <mblair1@home.net>
Sent: Monday, November 13, 2000 11:28
Subject: Re: [MV] M34 vs. M35A2
>
> ----- Original Message -----
> From: <mblair1@home.net>
> To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
> Sent: Sunday, November 12, 2000 23:45
> Subject: Re: [MV] M34 vs. M35A2
>
>
> >
> > DDoyle9570@aol.com wrote:
> > > While I have never seen tabulated data to support this, I suppose the ground
> > > pressure is lower on 10 900x20's is lower than that supported on 6 1100x20
> > > (although the gross weight of the 6 wheeled vehicle is 410 lbs less than the
> > > 10 wheeler).
> >
> > I think you're correct. According to my 1965 M44-series operator's
> > book, the recommended highway pressure for singles is 70 PSI, and it's
> > 50 PSI for multifuels with dual tires.
> >
> > I think that with pneumatic tires, the ground pressure will be roughly
> > equal to the tire pressure (ignoring support due to the rigidity of
> > the sidewalls, which I would guess is negligible for most common
> > tires). The air in each tire will apply an equal force to each square
> > inch of the interior of the tire, and the tire will flatten until the
> > area of the contact patch times the tire pressure is equal to the
> > weight supported by that tire. Thus, the ground pressure will roughly
> > equal the tire pressure, with the total area of the contact patch
> > varying depending on the load and the tire pressure.
> >
> > I'm no tire expert... I'm just applying a bit of physics to the problem.
>
> > Mark J. Blair, KE6MYK mblair1@home.net
>
> The following is sent after working a graveyard ( 3rd ) shift. I am no
> mathematician or physics expert but lets say your truck weighs in at
> 24,000 lbs., it rides on 10 tires therefore each tire supports 2,400 lbs.
> If your truck has 6 tires than each tire supports 4,000 lbs. You can see
> the need for larger tires. Each tire where it meets the ground, ( footprint) ?
> uses X number of square inches. So lets say your 10 wheeler @ 2,400 lbs.
> per tire with a footprint of 10 square inches now has a footprint of 240 p.s.i.
> If your truck has 6 tires , with a footprint of say 16 square inches now
> uses a footprint of 250 p.s.i. When you air down for operation in sand you
> increase the size of the footprint and decrease the p.s.i.
> The above numbers were just made up for the sake of working this out
> and in no way should be taken as actual weights , square inches, and
> p.s.i. Another way of looking at would be to take a M-48 Battle Tank
> with its large track sitting on the ground only uses 11.87 p.s.i. of ground
> pressure. If anyone can explain it better please do.
> Jim Wiehe , VA3JHW
> mail to : j.wiehe@sympatico.ca
>
>
>
>
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