Sean

VOSA have always used this method of testing imbalance there own truck test, including the 30% limit.

However there automated RBT are programmed to ignore the result (from a fail on imbalance point of view) if the LOWER wheel reading locks.

You don't need to be very bright to work out that measuring imbalance on locked wheels is pointless, but then the same team decided that deliberately disabling SRS lights is acceptable practice !

However in fairness vosa are aware of the problem The special notice issued regarding these changes does point locked wheel could result in incorrect fails,not sure that the advise for overcoming this is totally correct but I am sure you can arrive at a accurate result.

I must admit I thought the intention was to to calculate the imbalance at max braking (i.e. just before lock ) which would be logical.

I guess we are just enforcing yet another questionable EU directive.

Cheers Aidan