RE: Twin Otter 125inch wingspan
Lins:
We went per plans, 5 1/2 inch mains, 4 1/2 inch nose; Dubro "Big Wheels"; They are big donuts, and inflatable. I fly off grass and my landings have occasionally been, well, er, let's say less than stellar.
These come pre-drilled for 3/16 inch axles. The plans show two landing gear rods, one 3/16" and one 1/4". The plans show the axles on the 1/4", but we put them on the 3/16" to avoid the risk of off-center drilling on the wheels which are expensive.