I have seen many discussions on changing tires and how bad the original Hankook tires were. I have a 2015 K900 that now has 101k on it and I absolutely love the car except for one thing, the slight vibration that starts at 43 mph and continues until about 60 mph. I have had it for about 30k miles, changed the tires, road force balanced, the whole deal and nothing changed. It is a vibration I can feel through the seat and steering wheel. The steering wheel doesn't wobble, it's just a vibration. The car is smooth as silk until I hit the 43 mph mark and then I start to feel it. New tires are about 3 months old and didn't change a thing. I know there have been many threads about tire vibration but has anybody had this issue and it wasn't the tires? What are some things I should check. I did the 100k mile service and changed out the plugs and coils and no change. Again, love the car, but it is a continued annoyance. No accidents or potential frame damage.

It sounds more like a balance issue, but you may have a bent wheel. Check to see if you have a wheel-straightening shop near you. They should be able to check to see if it's out-of-round.

I also have a 2015 and have had the same exact problem. Mine goes away after I drive the car a bit and is definitely worse after it has been sitting. I don't think it is the tires. Over in the FB K900 group many people have complained about the same issue.