Is this rust?

[Bearcruiser]

Is this rust or no? If so is it bad to the point it will get worse over time or no?

Taken from the front passenger tire under a 07 4runner

 

[2016 4Runner SR5]

Nope, mud. Wash it!

 

[Bearcruiser]

Thanks!

 

[Cloud9]

lol you guys are funny!