Why do dogs smell car wheels/tires?

I've had several dogs over the years and for some reason, they have all been strangely fascinated by the smell on car wheels/tires. They seem to be more interested in the wheels. I understand that the tires are probably going across a wide variety of interesting-smelling surfaces, but their interest definitely seems to be on the wheel itself. Anyone have any ideas?Why do dogs smell car wheels/tires?
Good place to find "pee-mail".Why do dogs smell car wheels/tires?
as bc dawg mentioned - dog mail - other dogs urinate on the cars tires, one of my male dogs favorite hiking spots, since my dog is taller than most, his shot range is much larger, so there is more to sniff, littler dogs come around and try to figure out how dominate my dog is.Why do dogs smell car wheels/tires?
they have lots of different smells on them just think everywhere your car has been in just one day and you can imagine that it's a noses buffet
It most likely holds the smells and yuck. This probably makes it smell more powerful.

gas mileage