Chevrolet C60s - Front Wheel "shimmy"

[cordenj]

For reference photos of the 6-degree wedges.

Had the offer of two wheel and tyres this morning (thanks Neil) that are old but know to be ok on a guntractor. So collected them and fitted to the Chev. Just back from short test drive and they make ALL the difference. While there is still shimmy on hitting a pot-hole/drain cover at 20+ mph it is controllable and nowhere near as violent of with the other bar-grips.
Photo shows problem "round-shouldered" tyre about to be replaced with the very old "square shouldered" type.

As the large wedges appeared to make matters worse yesterday, I'll fit the 3-degree one in place again as the front springs have still "sunk" and the caster angle will be affected.