what's the difference between snow tires and black people ? snow tires do n't sing when you put chains on them
Is that a reference about slavery?
It's a metaphorical joke that alludes to the stereotype that blacks are always late to everything.
Slavery is an awful part of our history and affect people even today. Making jokes about it can be hurtful. You should consider learning more about black history from books so that you can understand why those jokes can be hurtful.