15k as in they were replaced before? most carry lifetime warranty.
First i would jack up car and see if tire rocks, has play, trying to determine if brakes, wheel bearing or axle, you would typically of heard a hum or noise every time you turned either left or right before it got this bad. If you had heard clicking when turning then likely one of the half shaft joints has gone bad...
then I would inspect the brake caliper and pads, look for excessive brake dust on the rim, look for marks inside the rim as well, in case the caliper is hitting a wheel weight, if so and the caliper pins are good, check ball joint, turning a hard corner form a stop would put extra load on a weak ball joint, place pickle fork or tire iron between a-frame and strut and see if there is any play, there should be none, so far so good continue on, if not fix what you have found...
Next I would pull half shaft out and after checking the bearing again, spinning to see if it makes a dry noise, you know after you listen to a few, then rotated the outer joint in a circle and lift end up and down, you could get good idea if that joint was bad from problem you experienced without pulling boot off and really inspecting for galling and so forth, it has balls and a cage and if grease dried up, or boot tore, it will hop over the bad ball giving a crunching sound..
inner joint is tri-poid , needle bearings and spheres with top and bottom cut off and hole inside on a 3 way yolk, slide inwards and outwards while twisting, should be tight, but with anything over 10k the spot where the wheels are straight may have minimal play by now, but that joint would most likely cause vibration at highways speeds not what you are experiencing.
Anyhow that is basically how I would try and determine what could be causing your condition, good luck, ask if anything was confusing, but sounds like you know how to swap a half-shaft so you should be good..
