I've had two experiences with the balancing cones. The first time with 4/4 wheels and the second time with Roadster wheels.
The inner cone was fine. A good fit on the balancer shaft, but in both cases we couldn't get the wheels to rotate concentrically using the outer cone. They had a wobble. So we did what you're told not to do, and used a taper cone which just fitted the inside of the wheel centre without fouling the spokes.
Using this, the wheels rotated absolutely straight, and the balance is spot on.
My local garage know what they're doing, but we just couldn't get the outer cone to work properly.
Note also that whereas most tyres these days come off the outer rim, with Roadster wire wheels, the tyre comes off the inner rim. This is because of where the channel is located on the rim, so is worth mentioning to a tyre fitter if you have Roadster wires. Not sure about Plus 4 wires, and it never came up with the 4/4 wires so I'm thinking that they are conventional.
