I am going to be ordering up a set of these non v-bar chains for my tractor with R4's:
DUO-Grip tire chains for farm tractors
I have a similar set that I use on 18x20x44 R3s, they work much better on those than on the similar size 17.5Lx24 R4s.
At the time there were two different vendors, one was tirechains.com - I don't remember the other one, other than it was a web order place with a similar name.
Here's where memory loss REALLY BITES - I don't remember which one I bought from, other than it was the one selling Peerless brand chains and they were drop shipped directly from Peerless in MN.
Around $300, but it was a few years ago.
Not absolutely certain that the Peerless are that much better just because of their point of manufacture, though I probably favored them because of that at the time.