TOM - In spite of the tops of tractor tires being rounded up where there's no load on them, where the rubber meets the road, or grass, or dirt, you will have a flat contact patch, which you want, for maximum traction. The fact those R-4 tires are already flat, and stiff because they have a thicker casing, more plies than a GT tire, they won't bulge where there's no load. Less flexing of the tire casing against the inner tube, plus greater resistance to punctures I would think. But they should still deform to smooth the ride over irregular surfaces. I've read on another forum that foam filled tires ride terrible on GT's, the R-4's should be better, maybe not as smooth as a 2-ply but not like a solid rubber tire.
My 23-8.50 Firestones are only 2-ply, same as the factory GY turfs. I run them around 8-9 PSI so the entire tread bar contacts the ground. Easy to tell on my dusty shop floor when the tires are damp. On my 982, the 26-12.00's are 4-ply, and 4-1/2 to 5 PSI is plenty. With those R-4 skid-steer tires 2-3 PSI in the inner tube, just to hold the tire bead onto the bead of the rim would be enough pressure.
I've always run my tire chains loose, so the cross chains flop around. It was no big deal on the old 70, no fenders. Plus it had turf tires, the factory 6-12 GY Pizzaw-Cutters. On my #1 snow mover, 23 deg. ag lug tires, a tight chain guarantees the cross chains will work their way down between the lugs and not even touch the concrete. So I run them loose also. Every time I clean the driveway, I have a couple times where I spin out, hit the brake of the spinning tire, other wheel spins. I raise the blade, back up then drive ahead and get the cross chains over the lugs, drop the blade and push the pile of snow I spun out on just seconds before anywhere I want it. So no deflating tires, and reinflating them here. Plus when the #1 snow mover had 50 gal. of CaCl in each rear tire, there wasn't a whole lot of air volume to let out.
If your side chains are sized properly, there's NO WAY a chain can ever work it's way off a tire. I've used chains on CC's for over 30 yrs, and on large Farmall's for 20 yrs. NEVER EVER had a chain come off. Well,.... I did loose a great little 6 ft long log chain off the Super H 2-3 yrs ago, had it drapped over the rear axle carrier wound around the clamps for the drawbar like Dad & I always did since before I was born. I saw it laying in the snow a minute after it fell off. It's the handiest chain I have, use it ALL the time with the loaders to pick & carry stuff.
What works for me on my equipment on my driveway may not work for everybody. What works for you on your driveway probably won't work for me. And since Don T has a sealed blacktop drive, he doesn't want to spin chains on his sealer, while I gave up worrying about scratches on my concrete 20 yrs ago. Christmas Day 6 yrs ago SON & I cleaned the driveway before X-mas dinner, had both loader tractors out, Super H w/chains, M without chains. I could move more snow with a whisk broom than the M would move without chains on the concrete. But if you got it off the concrete, it did O-K on the crushed rock or frozen dirt/grass. But if you ever spun a rear tire, you were stuck. I had to pull SON out of situations 2-3 times. I've even had the Super H spin on frozen ground with the chains where I had a bit of a problem getting back out.
I think an ATV tire with a softer rubber compound on the tread rubber would work better on a GT for snow remoaval. Even an "HDAP" tire would be better, do a search, lots of discussions on other forums, but I don't know if they would be better than chains. They might be, but I don't think they make a 12.4X38 or 13.6X38 6-ply ATV tire. I'm still waiting for someone to put a pair of Bridgestone BLIZZAK's on a CC and see how they work for snow removal with no chains.
