I know this is a full on winter tire thread but wondering if anybody has specifically compared nitto Ridge grapplers and toyo r/t. I go to Tahoe a bit and have blizzaks on the suv I can throw on but I'd prefer to just drive the truck.
Sorry, I got carried away and wrote a novel. Quick answer - haven't compared those two but I have experience with the NRG's and don't recommend them for wet pavement or snow/ice.
I run Nitto Ridge Grapplers on my 4R. But I try not to in the winter. Actually wish I had bought something else for this (second set). My experience is that once they wear down just a little bit they are awful on wet roads and have poor snow traction. Personally I would NEVER recommend NRG's to someone that wanted "good" i.e., safe traction in snow or wet pavement. But, maybe they perform differently on a heavy truck.
Now, having said that, I did drive about 1,000 miles on mostly ice between Missoula Mt. and Northern Michigan this year pretty much following a big snow storm (I started and returned to the Seattle area), That set of NRG's were almost new and they did much better than I expected on the 1,000 miles of really really bad very icy roads. It WAS white knuckle and I did NOT feel like I had consistently good control (but the road was mostly empty except for the trucks in teh ditch). I think the tires did "okay" because 1) tires were new, 2) the vehicle was probably a few hundred pounds over max GVWR, 3) most of the drive the speeds were not much over 40 mph. Also, occasionally there would be a vehicle ahead of me (typically a pick up truck) and I'd just watch to see when they started going sidewise and the slow down a little. LOL.
For THIS winter I tried something new with the 4R and bought the Nokian LT winter tires with studs. Previously had been occasionally running a very old set of Toyo something or other (Blizzak equivalent) but they "aged out" so I finally tossed them at around ten years old. The Toyo winter tires were similar to Blizzaks. They were "fine" and definitely better than summer tires...but not like the Nokian Studded LT's.
We've had a very light precipitation and light snow year here in the Seattle / Cascades, but I was fortunate enough to use the new Nokian studded LT's during one heavy snow event traveling to the ski area at Snoqualmie Pass.
The road had a layer of ice with snow on top and traffic was very slow. Chains required for trucks. With those studded Nokian tires, I felt like I was running on Velcro. I grew up driving in the snow to college in the Upper Peninsula of Michigan, and actually grew up in Ann Arbor, so I have lots of experience with snow driving. I've NEVER experienced anything as confidence inspiring as those Nokian Studded LT's. When driving to the Pass in those fairly bad conditions, with slow traffic and slippery roads, I simply pulled into the mostly unused far left lane and passed everyone. I am well over 60 YO and reasonably cautious, so no I wasn't acting like a crazed youngster. Rather, I had better control of my vehicle in the thick snow lane than everyone else did in the other lanes. I was shocked how well those tires worked.
Anyway, I'll end where I started - I would NOT recommend Nitro RG's as a winter tire. They might be marginally okay when new but I don't think it will be confidence inspiring. If you know the weather is going to be snowy and icy I'd put the Blizzaks on the SUV and drive that instead.
BTW, the reason I bought the studded tires for the 4R was because I did not need to drive that vehicle many miles around town in the lowlands where there generally isn't any snow. I have other vehicles for that. And with my new Tremor, I had to decide if I wanted to buy winter tires this winter for that vehicle - and I just wasn't ready to decision winter tires for the new truck before doing some discovery on how the non-3PMS duratracs performed. So I took the easy (expensive but easy) way out and put the Nokian Ice Killer's on the 4R and I am happy I did. I also happen to have two sets of wheels for the 4R and one set was "unshod" because I threw out the Toyo winter tires last spring despite there be useable tread left. I threw them out so I wouldn't be
tempted to keep running them at such an old age, despite remaining tread.
As I think I mentioned in a previous post, I am willing to pay for safety and don't mind having capital tied up in a second set of tires - either way I'm going to (usually) eventually wear out both sets of tires.
FWIW, my current plan is to see how the Tremor performs with the non 3PMS Duratracs on snow and ice. If I don't like the performance I may just sell them and buy something that is 3PMS and well liked / well reviewed for wet road and snow performance. Something like the Falken Wildpeak's (but the new version of Falken WP's may not be as good in snow). With proven 3PMS tires on the truck as my "summer tires" I should be reasonably safe if I hit shoulder season snow/ice in those situations where I can't switch to the 4R. Since I live in Seattle we don't get a lot of really hot weather, so the risk of heat "melting" the tires fast in the summer isn't a big concern, and I rarely tow. Eventually I would probably buy a dedicated set of winter tires for the Tremor, but I'd like to see how a set of 3PMS year round tires perform as long as my aging 4R is available for bad weather duty shod with Nokian studded LT's "Velcro Tires" in the winter.
Those are my thoughts, FWIW and I hope it may be at least a little bit helpful for you.
My only regret is that this strong "El Niño" winter is having the the typical impact in Washington - relatively warmer weather and relatively lower precipitation compared to a "La Niña" winter (this is the opposite of the impact on CA). The precipitation variability can be significant between different El Niño years, but virtually every peak snow / precipitation year is a La Niña year. I guess we have at least 5 weeks left to catch up a bit on snow... And the odds are for a quick flip to La Niña by this summer... I think you mentioned a CA ski area. The snow has been light down in CA so far despite a strong El Niño which usually brings MORE precipitation to CA. Apparently other variables like the intra-seasonal "MJO" or one of the other intra-seasonal oscillations have interrupted the El Niño pattern so far this season, but that may give way. I like reading the monthly ENSO updates posted by NOAA.
Monthly ENSO update
CA Snowpack and Reservoir Visualizations
Your zip code maps to the Centralia area so you might be spared the mayhem of the Seattle metro area and I-90 
