The delays irritated the ministry of defence such that in February it asked the Ordnance Department when the type could be operational. It was promised that six vehicles would be completed in March and April each if 110 bulletproof tyres of the "Veil-Picard" type, which had been ordered in December from Michelin in France after export of the American "Seiberling"-type had been forbidden, were delivered on the due date of 1 April. In fact the tyres would never arrive; and bar a single vehicle to which bulletproof tyres had been experimentally fitted all M39s used normal inflatable truck tyres. But a far more serious deficiency would impede operational use.