I've been thinking about something like this recently. I've been looking
into buying new tires and find myself looking at the tires at a lot of
vehicles. I see tons of SUV's and trucks with all terrain style big tread
tires and I'm wondering, whats the point. Odds are the worst conditions any
of these vehicles will see is a dirt road why not just get some all seasons
like a passenger car and cut down on some road noise.
Welcome to the world of the 4 wheel penis extender..... if you have
microscopic cajones..... if you have doubts about your sexuality.... if you
wait until nobody is in the shower at the gym before you enter.... if it
looks like you are a victim of steroid over-use.... if your loving bride
giggles when you take off your shorts - you can always buy a lifted 4X4 with
big tires (even though the roughest ground you will ever drive on is the
speed bump in the downtown parkade).
We recently acquired an 06 H3 from the auction... it has some minor issues
(to be expected with all of 7000 kms on the clock, yeah?). On the front and
on the back are these MANLY tow hooks..... I'm talkin' D8 Cat earthmover
kinda towhooks..... Lift this puppy up on a hoist and we see a pansy assed
little all wheel drive wannabe... I'd be scared to take this thing over that
speed "mountain" at the parkade....
But MAN!!!! Lookee them tow hooks.... Anyone with towhooks like that has GOT
to have a "package" to be admired......
An' damn.... it is bigger than one o' them pansy assed Corvettes....
Do you believe a vehicle with a center of gravity an inch or two higher than
another is more likely to rollover? If you do how do you explain the fact
that six wheelers are not rolling over more often than cars or SUVs?
All other factors being equal (track width, wheelbase, overall weight,
tires, etc.), a vehicle with a CG one or two inches higher is more likely to
roll over. Semis roll over all the time. However, semis generally have a
wider track that passenger vehicles and are driven by professional drivers
who have enough sense to understand the limitations of their vehicles. Most
vehicles will spin out before they turn over unless you do some really
extreme maneuvers (quick changes in direction), there is an obstruction
involved, or there is another vehicle involved.
No vehicle other than a two wheeler is prone to rollover, none. The
difference in the center of gravity of a few inches is negligible. To make
a vehicle roll it needs to be tipped up over 45 degrees. Watch movies or TV
and you will see the will spin 360 degrees and do not roll, To make one
roll the FX guys must run one side up on a four foot ramp. Striking an
object and rolling is a result of inertia rather than the center of gravity.
Define "prone" to rollover. Vehicles roll over all the time. You don't need
a four foot ramp either. I've seen a VW Bug roll over in a flat parking
lot - it didn't even hit the curbing. Get almost any vehicle sliding
sideways and then have it contact something no higher than a curb, and tell
me you can't roll one over. And if you think a higher CG doesn't make this
more likely, then you need to take a remedial physics course. Tipping a
vehicle 45 degrees is not required. If the COG is high enough, you can tip
one that is not moving by tipping it at relatively small angles. Do a
diagram showing the CG relative to the wheels. As soon as you tip the
vehicle enough for the CG to be outside the wheel edges, it will roll on
over. For instances, an F150 has a 67 inch track. For the vehicle to be
statically stable at a tilt angle of 45 degrees, the CG must be no higher
than approximately 33.5". I would guess that as delivered the CG is less
than 30 inches above the ground. For a 30 inch height, the truck should
remain stable until the tilt angle is around 48 degrees (probably less,
since tires flex). However, if your raise the CG to 40 inches (and don't
change the track width), the truck would roll over if you tilt it to the
side at an angle of around 40 degrees. Raise it to 50 inches (again without
changing the track width), and the truck would roll over on it's side if you
tilted it sideways at little more than 30 degrees. Dynamic situations are
more complicated. In general tire loose traction before the forces are high
enough to tip a vehicle over on a flat surface. However, if you are doing
extreme maneuvers, you can induce a rollover by first shifting the CG one
way as the suspension responds to the maneuver and then back the other way.
Inertia is at play here. But again, the higher the CG, the more likely this
type of rollover is (all other things being equal).
Look it up in a dictionary. You are entitled to you own opinion but not
your own facts. I worked as an automotive design engineer for thirty years.
The center of gravity of a vehicle is located at a point below the center
line of the mass of the drive train. If what you believe were actually
true we should expect to see a few six wheelers on their side every day.
I am not sure what a "six wheeler" is. Are you talking about pickups like an
F350 with dual rear wheels? We do see trucks on there side almost every day.
There is no way you can claim that every truck loaded/unloaded truck has a
CG below "the center line of the mass of the drive train." That statement
doesn't even make sense. Are you trying to say the CG of the total vehicle
is lower than the CG of the drive train? This may or may not be true for an
unloaded truck. For a six wheeler loaded with rock, I am sure it is false.
On the other hand, it you are talking about a pick-up with dual rear wheels,
then the effective track width has been greatly increased, and this will
reduce the tendency to roll over.
For older F150's, the file available at
CG locations. They range from 25.5" to 29.9"
Well I guess we make a fine pair. You seem sure of a lot of things that are
not supported by facts.
Now educate me - what is a "six wheeler." It is not a term I hear. Is it a
duallie - two front tires on a single front axle and four rear tires on a
single rear axle with the tires arranged in pairs on either side or is a
"six wheeler" two front tires on an axle and two rear axles with two tires
each, or what? I know what a duallie is, a sixteen wheeler, a ten wheeler,
etc. I've just never heard of a six wheeler (well except for the old formula
one six wheeler - but I am sure you are not talking about that).
You showed limited knowledge here Mike.
You are talking a static roll over situation.
Dynamic, when centrifugal force is involved and the bottom of a wheel on
the outside goes up against resistance such as a road shoulder or curb,
etc. is what normally causes roll over.
A high center of gravity makes dynamic roll over more likely, just a
inch higher is all it takes.
If you believe those set up movies and vehicle ads you believe anything.
Unfortunately many do believe the ads and buy a vehicle that gets them
into roll over problems.
You are entitled to you own opinion but I guess you missed the part about
the effect of inertia in a rollover. The fact that the center of gravity is
an inch or so higher has little effect ;)
Of course raising the CG has an effect. The magnitude of the effect depends
on the intial CG, the wheelbase and many other factors. However, if all
other factors are equal, raising the CG will increase the risk of a
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