Because the size of brown trout can vary drastically based on where you are fishing, the line weights can vary drastically based on what you are doing.
Lakes, Rivers & Streams With Smaller Fish
Most fish will be smaller, so you won’t need heavy gear.
Spinning Gear
4 to 8 pound line depending on what you are fishing with
Fly Fishing Line Weights
Small Trout (3-4)
Average Size Trout (4-5)
Big Trout (5-6)
Bigger Lakes & Rivers with Big Fish
You will be able to catch bigger fish and will be throwing bigger baits and may be trolling.
Casting
12 to 20 pound line
Fly Fishing Line Weights
Stay with line weights in the 5 to 6 range. The smaller fish won’t be as much fun to catch, however, you are most likely fishing for big fish and you don’t want to lose a big fish.
Trolling
20 to 30 pound line, some anglers go heavier too. If you go lighter, you may have a tough time getting a big fish to the boat with how well they fight.