NRP87

Recently replaced the front right tire on my '99 Legacy 30th Anniv. that I bought used with 50,000 miles about 3 months back, and a few days after, I began to notice significant vibration in the steering wheel as I reached 50-60mph on my way to work (I commute 40 miles each way). I innitially thought the tires were improperly balanced after they installed the new tire, so I took it to my mechanic for him to look over. According to him, there was a 1oz discrepency (which he corrected), but no issues with the suspension. The very next day during my work commute, I noticed a significant decrease in the vibration, but it didn't seem as good as I was hoping for, so once I got to work, I checked the lug nuts on each tire to ensure none were noticeably loose. I discovered that on the recently replaced tire, the lug nuts were hot to the touch, and being that it was wet/misting out, it made absolutely no sense to me. I Googled it, and I've been finding an array of possible causes (bearings, brake pad, caliper, rotor, etc.), but being that I've never experienced it before, I'm not sure what exactly could be the real issue. Any insight or leads as to the probable cause would be greatly appreciated! Thanks all.