I seem to think you do at this point, but thinking back over the years, of all the tractors we had chains on, I did not always have them, nor when I was a kid, was I aware of these. First set I ever used was double ring on a '64 4000, no tensioner or anything on the outside of the wheel. The chains were the correct size, no modifications from another set or similar. Same set is used on our 3600 now and there are some bungy cords used on each side. Those seemed to slip off center at times, seemed like you need something. We had an IH 460 with turf tires, and just ladder type snow chains, no tensioners, I ran that one on the road a bit for snow plowing drive ways close by, no issues with the chains at all.
Now I'm assuming it may just be the fit and conditions you work in, observe how they ride on the tire, adjust if necessary. I don't install or adjust them real tight, just snug enough.
A few years back, after years of knowing I should have a set on my 850 here at home, I went and bought a new set of double ring chains from tire chain dot com, tensioners and small load binder. I have regular ag tires firestone road and field. I read somewhere that you should have those tensioners for a good fit which lessens the wear and to secure them properly. First year I had them, I jacked the tractor up, installed per the above, and never had to touch them again the rest of the season. I was towing some logs, clearing snow etc. Last year I had to fool with them a bit to adjust so they stayed snug enough to the tire, not wander etc.
The tensioners I bought are light chain, with S hooks and springs, at some point you determine what link to set the hook on for length and tension, and where to connect to the side chains, ideally so the center ring is about lined up with the rear axle ends, give or take.
There is some odd thing with this set, the cross chains close to the one end, and the link I need to connect to, to get them snug, something interferes a bit, as if I almost need to reset that one cross chain, the load binder makes it easier for sure. Brand new, ordered 13.6 x 28 so thinking about it, I almost thought there was a problem, I don't have the tool you can buy to work on these and move the cross chain. I don't have them on yet this year so I may not recall the specifics. Just seems I need some sort of tension on this set, given I may not be able to get the ends connected where I believe they should or would be easier if the cross chains were one link back on the ends, but assume they were built correctly, so I left as is.