A felt-like fuzz covers more than half of the sole of the sneaker. Flickr/Chris Evans If you've ever wondered why your Converse All Stars have fuzzy bottoms, you may be disappointed to find out that it has less to do with "increased traction" (as some have speculated) and everything to do with the almighty dollar.

The felt soles on the bottoms of the All Stars — and other imported soles — are a perfect example of "tariff engineering," explains the patent blog Gazetc.com.

Translation: The outsourced soles are specially designed to fetch a lower US import tax.

In this case, the special felt bottoms of the All Star cover more than 50% of the shoe's sole and allow it to be classified as a "slipper."

Here's the kicker: Tariff rates for importing shoes into the US can be as high as 37.5% and vary widely based on material used, but classifying the shoe as a slipper guarantees the rate at 3%. When you sell in the volume that Converse does, this adds up to a significant amount of savings. In 2013, shoe importers paid the US $2.4 billion in duty fees, according to trade publication Joc.com.

Gazetc unearthed this weird fact after searching the patent code of the sole (6,430,844) on Google's patent searching engine. What comes back is not a patent for a shoe at all, but something that looks like — and is described as — a slipper.

The patent. US Patent and Trademark Office

Fortunately, the fuzzy bottom doesn't affect the performance of the shoe.

Though some have complained that their Chucks tend to be slippery out of the box, many have reported that the fuzz is not permanent and completely rubs off after being worn for about a month.