On Sunday, June 11, 2006, at 10:52 AM, Dick J wrote:
> I was out on the interstate for the first time in about a month
> yesterday. I was surprised when a big, shiny big rig passed, and I
> realized it was a fourteen wheeler, not an eighteen wheeler. The two
> driving axles, rather than having traditional dual wheels, had monster
> ultra low profile, very wide single wheels. They looked like giant
> Corvette tires in about a forty series. This was the first truck I'd
> seen outfitted like this.
>
> Are these tires more common out west or anywhere else in the
> country? I guess they are what's to come. I wonder how much those
> four rear driving tires and their giant alloy wheels cost?
>
> DickJ
> In East Texas
"Super Singles" have been around for quite a while, but are suddenly
way more popular. They came about first, I think, on the steer axle,
so that higher loads could be put on the front axle. (Regular semi
steer axles are rated for 12,000# -- big tires/axles can bump that to
20,000#). Then Alcoa (or some aluminum company) made alum. wheels for
the wide tires, and the weight savings over a pair of duals was
significant enough that a couple of hundred pounds could be saved on
the gross weight of an "18 wheeler" by having only fourteen wheels.
And the aluminum wheels are less prone to breaking so last longer than
steel wheels. Yeah, the tires and wheels cost, but many loads of
freight could be carried over the life of the wheel/tire, each load
weighing hundreds (thousands?) of pounds more than what it could if the
rig had duals all around. That translates into lots more income --
more than enough to offset the additional cost of the big tires &
wheels. And anyway, lots of truckers like the snazzy looks of the
aluminum wheels as well as the weight savings.
Just recently I was reading that super singles have a new reason for
being installed -- less aero drag. I read that there's a percent or
two, here and there, savings on drag. Add up the fuel economy
improvement and the available increased payload -- and expect to see
lots more super singles.
By the way, the singles are mounted at every position -- steer, drive,
and trailer, and are on trucks everyplace I've driven in the past few
months -- east coast & midwest. If they're out west -- well, no
surprise.
Jon Wennerberg
Seldom Seen Slim Land Speed Racing
Marquette, Michigan
(that's 'way up north)
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