The tiny rubber hairs on the outer surface of tyres are technically known as vent spews, created during the manufacturing process. They are also called sprue nubs, tyre nibs, gate marks, and nippers.
However, whatever you prefer to call them, they neither help to increase the mileage of the vehicle nor have any other function on the tyre.
So, are vent spews useless? Well, to answer that we need to take a look at the tyre manufacturing process.
In the process of producing tyres, raw rubber is placed into a molding machine and air pressure is used to force the rubber to turn into the tyres' shape.
The molding machine has small vent holes that allow air to escape. With the air, tiny bits of rubber also escape through the vent holes, resulting in vent spews.
It helps to make tyres durable. Therefore, it can be said that the formation of vent spews is the byproduct of manufacturing the tyre correctly.
Once the tyre is manufactured, vent spews have no use. They don't affect the tyre's performance by any means.