Yep but they look like 1/2 inch crankarms to me, my Trike has got the f£^%"£(g things on it .Not all threads are equal.
A google search brought up :-
Thread Sizes
Most pedals have 9/16" x 20 tpi threads. Pedals for one-piece cranks are 1/2" x 20 tpi. Older French bicycles used a 14 mm x 1.25 mm thread, but these are quite rare.
Thank you, I did make sure that I was putting the correct pedals on, still won't fit. But thanks for looking!The pedals are either left threadded or right threadded - don't get that wrong or you'll damage the thread. Some kids bikes do have odd sizes, but assuming it's new the pedals should be correct.
They're not necessarily a 'childs' pedal, a lot of BMX bikes and American 'cruiser' bikes with the oversize 'inside out' bottom bracket and one piece crank use the smaller thread. My Trike is similarly afflicted by one of those cranks, I keep looking at getting an adapter to convert the BB to a normal one but they're £20 and then there is the crank to buy and I can't afford it at the moment.Search: "childrens bike pedal thread"
The first image looks like a 'normal' pedal to me (ie 9/16ths). Very likely the crank requires a child's pedal (1/2") (which is why the pedal axle thread is 'too big' (diameter) for it.