I’ve rented two U-haul trailers recently (and will probably in the future). Their safety chains have large hooks that are too thick to fit through the “holes” in our hitch. How have others dealt with this? Do I simply ream out the holes a little bit so the hooks can pass through?

 

Sounds like that is all you can do to make them fit.

 

NO! Do NOT drill on your hitch!!!! Doing so will compromise the structure/safety of the hitch design and if in the unfortunate circumstance where there's a road accident, you will find yourself in a real legal pickle if its determined that the hitch was altered in such a way.

The best way to do this is to get threaded rings that can fit in the hitch and accept the hooks from the trailer safety chain.

https://www.mcmaster.com/products/th...in-connectors/
(Don't get stainless, get zinc-plated steel)

 

The hitch is not being drilled here. Only the side holes below the hitch receiver are being enlarged.

 

What @H1Tad said.

buy some form of securely closing shackle that fits your hitch and allows for the connection of the larger hooks.

Enlarging the hole risks weakening the metal to the point it fails, and isn't worth the effort (you'll need to repaint the exposed bare metal to prevent rust).

 

Yes, but if the hitch fails for whatever reason the safety chains and their mounting area to the hitch assembly will undergo incredible forces and at odd angles as in many cases the trailer swings wildly and frequently ends up on it's side.

DO NOT DRILL OUT THOSE HOLES. You are asking for trouble.

Using "proper" threaded rings rated for the weight are what you need. I see on vehicles including 1-ton pickups all the time to allow for large safety chain hooks.

 

$3 a pop from Home Depot.

Any number of other equally simple, cheap, tried and tested, rated solutions.

Modding your hitch is a terrible idea and a solution to a non-existent problem.

 

 

The holes are not being drilled but the OP simply mentioned enlarging them.

 

Drill, enlarge, modify, tweak, widen, expand, change, or any other thing one could possibly do to those holes should be avoided. It truly is a safety component that should not be messed with, splitting hairs on method and doing so is at the owner's peril.