Allan,

I heard there were already provisions for tyre pressure variations in some
Canadian Provinces and had also heard that centralised tyre pressure systems
were already in fairly wide use in Canada. Such systems can vary tyre
pressure while the vehicle is moving and also provide constant feedback on
system pressure to the driver.

Also a guy named John Woodruffe who most of this group knows has done some
papers on the effects of tyre pressures on dirt roads (low pressure is much
kinder to the road). He is on [log in to unmask] and his snail mail address is
PO Box 189, Carleton Place, Ontario K7C 3P4 (though I haven't communicated
with him in quite awhile).

Also, Freightliner recently announced the availability or planned
availability of a very wide Michelin single designed to replace duals on
drive axles. I played around with one of the Engineering Department's
Century Class test trucks with a set of them on the drives several years ago
in Portland. There seemed to be no contraindications but you had better
check whether they are suitable for use at lower pressures on dirt roads.

I really think at least part of the answer is centralised tyre pressure
systems and duals in the short term just because with standard tyres there
are so many rubber compounds and treads available for the arduous conditions
you describe that you have the best chance of dialling in the best horse for
each course.

I'd be cautious about encouraging the use of the "super" singles or wide
singles like the Europeans use on their trailers, despite the significant
fuel advantages and the fact that you can spread the spring centres and thus
increase stability. They are harder on pavements than duals. That might not
make a big difference in Europe or even in most of the US, given the
thickness of their pavements etc but in Australia where we have thin
pavements and in Canada where the base turns to pus when it thaws in the
spring I wouldn't be encouraging the things.

A couple of centralised tyre pressure systems are now being marketed by big
road transport industry suppliers. Eaton might be one of them. They are
becoming fairly common in Australia in logging applications and have greatly
reduced damage to forest tracks here, especially in the wet.

Remember this spiel is from the point of view of a trucking writer not a
scientist or engineer. I am reasonably certain of the veracity of the above
statements but it would take me some time to properly verify the bases.

Cheers,

Bob Murphy MCIT
IS Edit Transport & Technical Communications
PO Box 111
Campbells Creek VIC 3451
AUSTRALIA

Tel: + 61 3 5476 4408
       + 61 3 5476 4474

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----- Original Message -----
From: "Bradley, Allan HI0" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, December 14, 2000 7:55 AM
Subject: Enhancing commercial vehicle traction on sandy roads


> Hello colleagues,
>
> I am writing to see whether someone can suggest some solutions to a
> transportation challenge that we have here in Saskatchewan, Canada.  Our
> Highways Department recently opened a winter road of about 150 km length
to
> improve access to the far north of the province.  The locals have decided
> that they want to try using the road during the summer at slow speed (<50
> km/h).  However, commercial trucks with standard tires and wheels are
having
> difficulty negotiating the rocky outcrops and pockets of sand (typical
> Canadian Shield landform).  Can anyone suggest any technologies that might
> be tried to increase the mobility of the commercial trucks on this run?
>
> My thoughts so far are:
> reduced tire pressures (Tire Pressure Control System-controlled)
> Super single tires
> Sand/All Terrain traction tires like the Michelin XS or XL 18R22.5 or
> Goodyear 445/65R22.5 G178
>
> Thanks for your assistance with this.
>
> Al.\\