More than likely this is a tire vibration from sitting for so long. What happens is they get flat spotted from sitting on the same spot of the tire and the rubber literally gets flat.
Normally this is felt at all speeds if they are flat enough but if it is not then just at higher speeds.
I would start with inspecting the tires for flat spots or uneven wear. If you don't see it then you are going to need to have them balanced on a machine called a road force balance machine. Basically this puts a roller to the tire and simulates the tire driving down the road to see if there are any vibrations rather then just spinning the tire to measure it which will not show these types of vibrations in most cases.
Let me know what questions you have on this and what you find. Thanks
Thursday, April 1st, 2021 AT 10:45 AM