The reason you are experiencing sling is because you are probably using a silicone based tire dressing. Silicone does not get absorbed by the rubber yet sits on the surface. Unless you buff it in (you lose the intense gloss this way) you will experience some "sling" onto your paint and wheels. The benefit of silicone based dressings is a more durable high gloss. Silicones dressings can also potentially dry out and brown your rubber over time, so it's not a dressing I turn to.
I use a water based dressing, such as
Poorboy's Bold 'n Bright, that gets absorbed into your rubber and conditions the rubber keeping it flexible. Since they get absorbed into your tires, it usually does not sling up onto the paint, unless it is OVER applied. The downside is the dressing is not as glossy and not as durable, but it is safer for your tires and your paint. It's a trade off usually.
George