What specific problems are you seeing with the saw? Bearing problems will be pretty obvious. New tires won't hurt but if the current ones aren't falling apart, probably won't improve things much. Everything I've read says tires are the last thing to upgrade. Maybe all you need is a decent tuneup. A BS running with wrong tension will do all sorts of wonky things. And, if your guides and thrust bearings aren't right you won't get decent results. The alex snodgrass video is a great place to start. My gut instinct says less than an hour of tinkering will improve your saw a huge amount.