Jim,
Thanks for the explanation. I still don't see how the tube can supply
more pressure to the bead area than the air did, but that it might hold
the air (pressure) in place for a moment longer may be the answer. I'm
waiting to see if someone can answer the question about the shape of the
rim used on the tubed MGB spoke wheels and the tubeless MGB disk wheels.
Perhaps that wil tell us more.
Len, do you know the width of the TR3 wheel? The size of the radial
tire?
I still wonder if the roll-off-the-rim problem is not in some way related
to modern tires being used on T cars, tires that should be mounted on
wider rims. I have been following the discussions of MGB obsolete size
165x14 as the suggestions about different sizes pass by. MGBs had 4 inch
wheels originally, 4.5 on the GTs, then on all cars, as I need to get a
new set for our MGB-GT this winter.
Some info collected from the Workshop Manual
Engine Wheel Std
Tyre Optional
18G, GA 4J x 14 5.60 tubed 155 (not
described)
optional 4.5J x 14
18GB 5J x 14for GT 165x14 for GT
tires not described
GHN4/18GD and 5.60 "
GHN5/18GG 155SR "
165SR "
Competition 14x5 no tires
mentioned
Equip 14x5.5 70 spoke wire in Comp section
There is not consistent description of wheel or tire in the various
sections. F'rinstance, in one place it shows the owner changing a tire
and tells how to install a tube; in another the text states that all
tires are radials.
Bob
On Tue, 14 Oct 1997 16:42:19 -0400 (EDT) JMerz140@aol.com writes:
>Len, Bud and Bob,
>The incident Len cited is exactly what was identified to me long ago
>as being
>the problem with not installing tubes on our TD wheels. As the force
>of the
>abrupt turn pushes the tire bead toward the centerline of the wheel,
>the air
>is dumped the same as in the case of a blowout and away you go! The
>tube,
>as I understand it, doesn't actually keep the tire on the rim but it
>helps
>restore the bead to its normal position on the wheel as the wheel
>revolves.
> This restorative action is enough to retain the tire where it
>belongs. Now
>I I've spouted off everything I think I know about the subject. From
>the
>standpoint of safety, the reason for the tubes is not that you plan to
>make
>hard turns, it's for the unexpected occasion when you have to do the
>maneuver
>to stay out of other troubles.
>As for the safety rim, as best I remember, the "safety rim wheel" was
>first
>touted by Chrysler products back in the 40s maybe the later 30s. I
>have no
>idea what the physical characteristics of the improved wheel was but I
>imagine it was some sort of a retention bump on the bead seating area.
> Maybe
>somebody out there knows or remembers more details but I think the
>safety
>wheel preceded the tubeless tire by many, many years. My turn to get
>off the
>soapbox. Jim
>
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