Although the Ford Mustang is built year-round at the Flat Rock Assembly Plant just outside of downtown Detroit, Michigan, not all of its trim packages enjoy the same 12-month production cycle. The reason why is actually very simple. Ford Authority has learned that Mustang trims equipped with the super sticky Michelin Pilot Sport Cup 2 tires are not built during winter months, specifically from November until March.

Those aggressive tires are designed specifically for superior track performance thanks to superior grip levels. They are, more or less street-legal track tires. Needless to say, racing slicks aren't ideally suited for winter and the heavy snow and ice the season brings.

The tires are made from a very soft compound that creates two cold-weather problems: the tires can lose traction during the Mustang's certification dyno run during the final assembly line stage. And second, Mustangs are loaded onto a freight train for transport nationwide (and globally), but that Cup 2 rubber can't handle the steep ramp onto the trains.

So, for eight months out of the year, the MPSC 2 tires are unavailable for the following Mustang models: Shelby GT500 with the Carbon Fiber Track Package, Mach 1 with the Handling Package, and the GT equipped with the Performance Package 2. Before they were retired, the Shelby GT350 and GT350R also had these race-ready slicks.

Ford has not officially confirmed this information and we've reached out to the automaker seeking additional clarification, but not equipping Mustangs with those tires during winter months does make complete sense. Mustang customers who live in regions of the country with mild winters may be able to enjoy what these tires have to offer year-round, but the fact Ford apparently can't get the vehicles off the assembly line properly is an issue without a workaround.

Anyone living in parts of the country with harsh winters, such as Michigan, will know the dangers that a harsh weather can bring. Either equip your Mustang, or any other rear-wheel-drive vehicle, with winter rubber or park them inside until the frozen ground thaws.