I have recently got my k5 road worthy again and I am now getting to "feel" the "gentle" ride my 38" swamps(non radial) are giving me. I do have a question though regarding what i am experiencing.. 1) When I start driving I am gettin a pretty sizable rumble and shake. This smooths out at aroun 40 mph....is this the tires? I ask because I don't know if its the driveshaft, tires, alignment or all of the above! Since it does smooth out, I was thinking it was the tires... any thoughts?