First off, hello. I am new to this forum. I've got an 08 expedition 4wd (138k)

I have 20 inch F-150 FX4 wheels with 275/55 for the summer and stock 18's with Blizzaks or something like that for snow and ice in the winter.

When I use the 20's I get a vibration about 75mph, goes away around 80-82.

When I use my squishy winter tires I don't get the vibration at all.

Anyone else have a similar experience?

I have already had the 20's re-balanced and it didn't change anything. I am guessing its all in the wheel/tire combo since I don't get it with the other wheels/tires.

 

Could be a bad tire, sometimes the internal cord breaks.