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After investigating alternative tires for my current M37 project, I've
opted to stay with the original NDT tread. I have a couple of other 4x4s
that I can use when the roads are icy.
Here in Salt Lake, it snows frequently during the winter (averaging
maybe once per week), and we live on a steep hill overlooking the
valley. We get more snow up here than down in the lower portion of the
valley and the steep roads in this section of town can become very
treacherous until the plows and salt trucks arrive. I also travel
frequently through the surrounding mountains for both business and
recreational purposes, and there is plenty of white stuff up there (most
of the 2002 Winter Olympic Game venues will be within about 30-45
minutes' drive from our home).
I've owned two other vehicles with military NDT tires (MB and GPW), and
I've actually had pretty good luck with the NDTs, except on VERY
hard-packed snow and ice, in which case they are noticeably slicker than
a good radial snow tire. In softer, deeper snow, NDTs seem to work
admirably. They also work well on snow-packed roads in very cold
conditions (cold air and cold ground), in which case the snow tends to
remain granular for a longer period of time and be re-formed by your
tires as you drive over it, even though others have driven over it
before. Naturally, conditions will vary considerably.
I want to emphasize that on ice, all tires are pretty slippery, unless
they're studded. A tire with lots of fine siping will generally do a
little better on ice, due to its many tiny gripping edges. Radials will
be somewhat better than bias-ply tires on an icy surface. Some of the
newer silica-impregnated tread compounds may perform a little better on
ice, not so much because of the edges of the crystals themselves, but
because it tends to make for a more stable tread compound that is
perhaps a bit stiffer, giving the edges of the tread a somewhat better
bite. I suspect that the silica also helps keep the rubber from
softening too much at high temperatures (not applicable in this case).
Keep in mind that radials are NOT necessarily better under all
conditions. When driving in extremely rugged terrain, such as the trails
in Utah's canyon country, non-belted bias-ply tires are often the tire
of choice because of their ability to conform to the rocks, ruts, and
convolutions, wrapping themselves around these obstacles rather than
concentrating the weight on smaller areas, such as the tops of pointed
rocks, which is what happens with belted tires under those conditions.
When non-belted bias-ply tires are used with low pressure, this ability
is magnified. Also, radial sidewalls tend to be more vulnerable to
damage, partly due to the lack of criss-cross plies, and partly because
the sidewalls hang farther out over obstacles than the sidewalls of a
bias-ply tire. The Dick Cepek tire company and several others make
non-belted bias-ply tires for off-road use and they charge a premium
price for these guys.
I recently managed (unintentionally) to poke a small tree root right
through the side of a Michelin tire on my pickup truck. It went through
the sidewall like a hot knife through butter. I didn't even feel a bump
when I drove over it at about three MPH.
One approach would be to carry a set of chains with you and put them on
only when needed. The lighter-weight cable-type chains may not last as
long as the link-type chains, but they aren't as rough riding, they
install quickly, and they work OK on ice. Neither type is good for
high-speed driving.
If you don't mind paying big bucks, Michelin makes some military-type
radials (XCL XZL XL etc.) that have steel-ply sidewalls as well as steel
belts under the tread. These aren't manufactured in the US, but they are
available. In the 9.00R-16 size they run between 325 and 345 dollars per
tire in the US (Gordon McMillan says they're even more expensive in
Scotland). Don't know about the 20-inch sizes.
I think it boils down to what kind of driving you'll be doing and how
often the tires would be a disadvantage to you as opposed to
advantageous. If authenticiy is important, stay with the original
pattern and keep a set of chains handy.
Regards,
Alan
(Salt Lake City, Utah)
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