Like others have said, it could be balance..
Also could be tires that are out of round..
its possible... my 17's do the same since I got them
balanced twice, and now that the tires are almost shot
the vibration is worsening... i've actually had the car up in the air
and idled the car in first gear... and noticed mine were out of round.
in the spring I won't be buying cheap tires again(federal 595SS's)
i've returned to my 16's
with just race tires on them, and they are smooth rolling.
so i know its not car specific in my case.
