We know there are many things that have wheels—a car, a motorbike, a bike and even wheelbarrow but when somebody refers to their wheels they are talking about their car.      

Example 1)

“Hey, can you pick me up at 3?”

“Sorry, I can’t. I don’t have my wheels at the moment.”

“Why?”

“I had to take it down to the garage, there’s something wrong with the engine!”

Example 2)

“Nice wheels!”

“Thanks, it was a birthday present from my dad!”