Probably around double the maximum engage distance, you'll be hitting outside 32bit number limits once you pass there

Distance units are meters (Toris are gigantic as far as the physics engine is concerned), so it's likely has a max range of around -4,294,967,296 < -> 0 < -> 4,294,967,296 meters, OFC there could also be a hardcoded limit hidden in there somewhere - but if there isn't, I guess it would be around 8,589,934,592 meters edge to edge before things go wonky or crash