Truck tire explodes at 220 mph?

There's an argumentative blowhard in another NG who claims to have
been an editor for a British trucking magazine a few years ago
(apparently before he was fired), and he has come up with the same
strange story twice.

He claims that if you jack up one tractor wheel and run the engine so
the tachograph indicates 55 mph, the spinning wheel can turn 220 mph
and explode.

Does this make any sense to professional truckers?

Here are the two versions of his story:

1. Last year or the year before we were asked by a coroner to carry a
news
story, for the general benefit of the truck industry. Some workshop
was changing the brakes on the back wheel of an eight-wheel topper.
While the wheel was jacked off the ground they decided to test the
tachograph as well. They didn't use a rolling road - they just chocked
the other three wheels and ran the engine up through the gears with
one wheel out of the four rear driving wheels off the deck.
The truck, of course, had a four-way differential on the rear bogie
and *all* the power was fed to the single unblocked wheel because the
other three, of course, were blocked. At an indicated 50mph the rear
wheel was revolving at 200mph. The tyre, which had been properly
repaired some time before, exploded due to the centrifugal force on
the rim (1200g is a figure that sticks in the memory, for some reason)
and killed a mechanic....


2. And further to that, when I was editing a commercial vehicle title
some years ago, we got a report forwarded by a coroner (always a good
sign) with a letter saying: "Can you publish this to make certain no
idiot ever does it again?" It ws an eight-wheeler tipper truck. Four
steering wheels forward and a
bogie with four driven wheels aft. The company wanted to replace a set
of brake shoes on one of the rear
wheels, and so jacked one wheel off the ground, and removed the shoes.
Before fitting the new ones, they decided they wanted to check the
tachograph was working properly, so started the engine, put the thing
in
gear, and ran it up to an indicated 55mph. Has anyone spotted the
error yet? Like all 'eight-leggers', it had a four way differential on
the rear driven wheels. Three wheels were still braked, so the diff
fed *all* the
power to the unbraked wheel. Which revolved at four times normal
speed, so 220mph, and took just 11 seconds to get there. The tyre had
previously been repaired, properly, but it wasn't designed
for this sort of stress and the tyre exploded like a bomb, killing
outright a fitter who just happened to be walking past....

.

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