Trailer for a toy farm tractor

My grandson received a toy New Holland farm tractor for Christmas.
Unfortunately he thinks anything with wheels is meant to move across the floor as fast as possible and bounce off walls etc. This has lead to me making replacement parts for the tractor and I decided a trailer would be nice addition.  

Everything is intended to be a tight fit so filing will be needed.
Without glue, replacement of parts is easier.

All the STL files are oriented for the way I printed them.

You will need 3 #6 x 1/2 machine screws and locknuts (M3 x 13 should work also)

The hole in the tire rims will need to be reamed with a drill bit for a tight fit on the axles.
For axles I used 3.5 inch 11 gauge finish nail cut to length (1/8 rod would also work). 
They are very close to 3mm diameter and I had many of them (metric rod is hard to find here).

Printed using PLA
0.4mm nozzle
0.2mm layer height
20% infill 
Supports used on all but the walls.

Since I was making so many parts I decided to also make a tractor.
I will be posting it in the near future