cases statistical analysis substantially improved on conventional intelligence. In some cases conventional intelligence was used in conjunction with statistical methods, as was the case in estimation of Panther tank production just prior to D-Day. The allied command structure had thought the Panther tanks seen in Italy were an unusual heavy tank, and would only be seen in northern France in small numbers, much the same way as the Tiger I was seen in Tunisia. The US Army was confident that the Sherman tank would perform well against the German "Mk III" and "IV" tanks which they expected to meet. Shortly before D-Day, rumours indicated that large numbers of Panther tanks were being used in the panzer divisions. To ascertain if this were true the Allies attempted to estimate the number of Panther tanks being produced. To do this they made use of the serial numbers printed on captured or destroyed German tanks. The principal numbers used were gearbox numbers, as these fell in two unbroken sequences. Chassis and engine numbers were also used, though their use was more complicated. Various other components were used to cross-check the analysis. Similar analyses were done on tires, which were known to be sequentially numbered. The analysis of Panther tank wheels yielded an estimate for the number of wheel molds that were in use. A discussion with British road wheel makers then allowed the estimation of the number of wheels that could be produced from this many molds. This in turn yielded the total number of Panthers that were being produced each month. Analysis of road wheels from the two tanks obtained yielded an estimate of 270 Panthers produced in February 1944 alone, substantially more than had previously been suspected. German records after the war showed production for the month of February 1944 was 276. The statistical approach proved to be far more accurate than conventional intelligence methods, and the phrase "German tank problem" became accepted as a descriptor for the statistical analysis used. See also List of German combat vehicles of World War II German tanks in World War II German aircraft production during World War II Comparison of early World War II tanks Military production during World War II French armoured fighting vehicle production during World War II Soviet armored fighting vehicle production during World War II British armoured fighting vehicle production during World War II American armored fighting vehicle production during