Steve Moore wrote:
>
> Chip Brown Writes
>
> > I replaced my HM Tourist (Avon)5.25x16 with 165r400 Michelin
> > tires/tyres over the weekend. The great big shimmy that resulted
> > therefrom is due, I suspect, to one of the tyres/tires not being
> > completely seated in its mounting, so I will remove all, re-examine,
> > and try again to balance same. Smooth ride is gone because of said
> > shimmy but even with the built in vibration but the car corners (with
> > 30 lbs of air) a whole lot better. The shimmy going down the Merritt
> > Parkway at (any) speed reminded me of a cross-ply versus radial debate
> > from years ago.
>
> This should help a number of people I know who want to fit radials to their
> 16" wheels. We can not source 165r400 tyre here in Australia. Can anyone
> suggest a source in the USA or UK?
> >
> > (There is, by the way, just enough room between the sidewall of the
> > tyre/tire in the front and the spring top to get my fingers in there,
> > or about 1/3 of an inch. Sisson warns about the whole mess deflecting
> > enough to tear up the sidewall: we'll certainly see about that as I
> > pull off the wheels this week.)
>
> Sounds about the same as any new Morgan to me. My 1972 4/4 fitted with
> 165x15 tyres has about the same clearance. I think you would have to be
> running very low pressures to cause significant deflection at the top of
> the tyre. Interestingly a friend has an MGA with the same sized rims(15 x
> 5 inch wires) fitted with 185 x 15" tyres. I tried the wheels and tyres on
> my car and the gap between the tyre and top of the front spring did not
> change significantly. Trouble again is that living in a remote and
> underpopulated part of the world 185 x 15" tyres of the correct profile are
> no longer available here.
>
> >
> > I remember years ago discovering, with a BMW 1600/2 that I had in
> > 1967-70 that replacing cross ply tires with radials created a world of
> > problems, with the macpherson strut suspension being much more
> > sensitive to radial tire imbalances than to cross ply tire imbalances.
> > I wondered about that with the Morgan, but decided that this
> > suspension didn't really resemble a mac strut at all (actually....) so
> > probably wouldn't have these problems.
> >
> > The question, as I see it is this:Do Morgan owners prefer radial or
> > cross ply tires? Part 2 of the question:, revisting a question that I
> > caught the very tail end of just after getting on the eemail list:
> > once suspension bits are rebuilt and set according to spec, how do
> > people cope with shimmy?
>
> The factory has been fitting radial tyres to new cars for upwards to 30
> years now. As the front suspension has not changed significantly since HFS
> increased the length of the kingpins in 1953 I think any problems
> experienced are more likely due to worn components or incorrect assembly
> rather than underlying design issues.
>
> Cheers
>
> Steve Moore
>
> Dr. Stephen Moore
> CSIRO Tropical Agriculture
> Molecular Animal Genetics Centre
> Level 3, Gehrmann Laboratories
> University of Queensland
> St. Lucia, 4072
> Australia
>
> ph 61 7 3377 0476
> fax 61 7 3377 0480
> email Steve.Moore@tag.csiro.au
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