What are the thickest strings made for a 4-string?

You could buy a light 5-string set and try the low strings?

Or... not?

 

Rotosound RS66LH (65 - 130) s/s r/w

 

Are you looking to tune standard, or lower?

If you want thick strings you should invest in a sub-contra bass.

 

The Carvin/LaBella .060-.115s are black nylon tapewounds, not "coated". They aren't high tension, the steel core is normal size, the nylon wrap makes it thicker than normal.

But if you use extra thick (not tapewound) strings like .065-.130 and tune your bass normally, you're likely to stress its neck beyond what it was designed for. If you damage the neck, the manufacturer is likely to call it abuse.

 

Couldn't, say, a graphite neck handle that kind of tension?

I'm still failing to see a reason why one would want strings thicker than .60-.115. Just get a 5-string.

 

Maybe, if it's thick enough or the profile is designed to take the tension. But whether it's wood or graphite, chances are it's designed for a range of normal tension. They aren't going to make the neck profile uncomfortable just to accommodate somebody who thinks it's kewl to play with an extra 100 lbs. of tension.