Tires have a rubbery and fresh "new car" sort of smell to them. This is a combination of the hydrocarbon oil vapours being released from the tire. It is not a particularly strong smell and you need to be close to the tire to smell it. The only time this is not the case is when vehicles are being raced or a car is performing burnouts. This extreme heat from the friction that the tire is experiencing causes the surface of the tire to vapourise and release the tires chemicals into the air.