I don't think it is a tire because you feel the vibration at such low speeds. However, if you have a spare you can try rotating each of the tires one at a time and see if it affects the problem. That will also allow you to insure the torque on the lug nuts.
Don't totally discount the pinion angle. If you have a worn suspension part as in bad control arm bushing it may cause vibrations as it allows the axle to rotate.
Please explain the vibration in more detail. Is it a lateral--side to side or more vertical, up and down in the seat.
The vibration in the steering column--does it feel like the wheel wants to violently go back and forth?
Because it comes and goes my gut says you have a bad bearing: unibearing, wheel bearing something that is rotating is not doing it properly.
I would bite the bullet and get this thing to a mechanic if you don't have the ability to put it on jack stands and run itwitjnthe tires off the ground.
Please let us know what you find.
Don't totally discount the pinion angle. If you have a worn suspension part as in bad control arm bushing it may cause vibrations as it allows the axle to rotate.
Please explain the vibration in more detail. Is it a lateral--side to side or more vertical, up and down in the seat.
The vibration in the steering column--does it feel like the wheel wants to violently go back and forth?
Because it comes and goes my gut says you have a bad bearing: unibearing, wheel bearing something that is rotating is not doing it properly.
I would bite the bullet and get this thing to a mechanic if you don't have the ability to put it on jack stands and run itwitjnthe tires off the ground.
Please let us know what you find.