Need for tire chains on Yellowstone trip

May. If it snows, it'll be wet heavy stuff that melts practically on contact. Pull off, wait until it melts and move on. It is foolhardy to drive on it (even with chains) if you know it'll be gone in no time at all.
Lynn

Pulling a trailer in snow is a bad idea on mountain roads. If it snows, just wait. It is good to carry chains all the time. Two sets is even better.

We went to Yellow Stone in 2013 the last week in may and they still had 6 feet of snow on some roads. Lake Yellowstone will be frozen over, the park really doesn't get going till May 31st. But it's a great time to visit not to many people and Artist point water fall is really flowing.

Yesterday morning checked the weather there. In West Yellowstone in the AM it was 13. We're considering a stop off there after RMNP the end of May also. Now we"re thinking maybe it would be better to stop off there on the way back, towards the end of June.

WebCams - https://www.nps.gov/yell/learn/photosmultimedia/webcams.htm

Just scroll down to see some roads - like the weatherman Looking out the Window.

West Yellowstone still on the side of the roads but looks to be an Easy Drive.

You know what they say about the weather in Yellowstone - "If you don't like it now, Don't worry it's going to Change:)"

Best of Luck,

Our daughter went to college at the University of Wyoming, which is down south in Laramie. She was there for seven or eight years (I forget) for undergrad and doctorate. Every year without fail, it snowed during finals in May.

We had rented a Class C motorhome from Denver so we could just camp in front of her house for graduation instead of driving back and forth to a motel. It snowed so hard on us on the last two days of the trip that we had to wait until the highways reopened so we could drive back down to Denver and catch our flight home. We barely made it.

So yes, expect snow in May.

I don't think I would bother with chains though. If it snows hard enough for chains, pull off the road and wait it out. Wyoming has plenty of vacant spaces and Walmarts.

If I think I may need them, I carry them

As long as your plans are flexible I would skip the chains.

Road opening dates:

https://www.yellowstonepark.com/news/2015-spring-road-opening

Fryer5, You can’t go wrong with a set of cables for the tow vehicle, and .....at least one trailer axle. They’re inexpensive, lightweight, and don’t take up much room. We keep ours with us at all times!