I agree with Mike on his recommendation.

I'm using the 3/16" hinges on my 28% Extra 300s, 14 lbs, as well as on larger aircraft I have built for people. These were the only hinges we used on 30% Extra 260's which weighed in at 22-25 lbs. The scale guys use them on some of the really large birds, but they use a lot of them.

The smaller hinges work great on models with surface thicknesses less than 1/4".

John