It is an indicator of tire tread wear.
Yes, because the tire gets hot and this causes the tread to wear faster.
It really does not matter how many there are as there are several around the tire. When the tread wear indicators appear flush with the tread you have 1/16" tread left and should look to replace the tires very soon.
Tread wear indicator
The four main characteristics of a tire tread are tread pattern, tread depth, tread compound, and wear indicators. The tread pattern affects traction and handling performance, while tread depth impacts grip and water displacement. Tread compound refers to the rubber's formulation, influencing durability and performance in various conditions. Wear indicators help monitor tread wear, ensuring safe performance as the tire ages.
When the tire tread wears down to the wear bars, the tires are ready for replacement.
Completer wear of tread surface -(creating an unsafe tire ! )
It is the rubber marker within the tread to show tread depth. It is also known as a tread wear indicator
In the middle of the tread area,
Tread wear indicator
As a general rule, you should replace your tires when the tread wear indicator mark is equal to the tread (The tread wear indicator appears as a raised triangle, or the letters TWI on the side of the tire). All ATV tires have a different tread life, depending on the application they are used for. And when used in applications they are not meant for, tires will wear more quickly. For instance, using a mud tire to ride on the road will wear out the tire much faster than using it in the mud.
A flat tire can lead to reduced tread wear and sometimes blowouts.