Vibration

[adal20]

I am l getting a vibration coming thru the floorboard when I accelerate it look like it is under my feet. When I drive over 55 miles I can hear humming from back . I replaced oil in rear differential recently , didn't replace oil in the front differential , I changed tires from hankook to Kuhmo , replaced rear brakes bearings on the back looks good . I checked propeller shaft it is not lose u-joints can they get bad ? Any Ideas ?

Thank you for all answers You guys gave me in the past

Adal20

[Max]

Did any of this vibe start AFTER any of the work efforts, and if so, which one?

If an engine mis / vibe...is the engine "tuned" (plugs, injector cleaner and filters at least)?

Automatic or standard transmission?

[adal20]

Hi !
It is automatic transmission , the reason why I did all that work was "hooming " on the back and floor vibration every time I drove over 45-50 mph ,I tried to eliminate some things that 's why I replaced tires,rear brakes & differential oil sometimes when car is idling it shakes little .Engine mounts ?Engine was tuned a 1 year ago with new spark plugs K&N air filter , pcv valve.

[Max]

I'm thinking two problems.

One...an engine mis-fire / shaking at idle (tune, injector cleaning or time to compression test). Any codes on a scan?

Two...the vibe / hum may be drive shaft related.