Okay. I ran the bald and beaten Goodyear Wrangler 265s on the highway. Shaking greatly reduced. Had some bad vibration in the front at 80 but these tires are horribly worn. As in, bald on one side, tread on the other. Also--looked at my spacers. Not sure what brand they are, but I'm willing to bet they aren't properly made.
Yes, I had quite an ordeal with my Falkens. Long post ahead. TL;DR: Had constant issues with vibrations on my Wildpeak AT3W 285/70R17s, Falken said tough shit. I had to have them cut down to be round. Tire life significantly shortened because of this. Bought Duratracs, ride is better and no vibrations. Much happier now.
I basically replaced the ENTIRE suspension, because numerous places told me the tires were good. Including 2 dealerships. One dealership balanced the tires and allowed me to watch as they use the Haweka adapter after I made a stink about them not being balanced and the tech did not want to use the adapter because it was "a waste of time". The manager told him to check one wheel with the adapter and it was indeed off. That still didn't really make much of a difference. They told me it was the spacers (I was using FJ Cruiser wheels). I took off the spacers and bought a brand new set of FN Countersteers ($900)...... and it didn't change anything except the thickness of my wallet.
After about one more month, I jacked up the 4runner and put it on jackstands. I put it in 4x4 and drive. Then walked around and looked at the tires. To my surprise, every single one of them was bouncing. The tread should be perfectly still when viewed, like you are looking along the road, but mine had a bunch of runout.
Pissed, I called Falken. I informed them I had a bad set of tires, from multiple Lot numbers. The lady said "I'm sorry, but Falken does not cover a complete set of tires for roundness. We only cover manufacturer defects." I politely inquired how 4 tires that are not round could possibly be considered anything other than a manufacturing defect. She said, I don't know, but that is the policy. I was dumfounded.
I took them to Discount tire and had them verify what I had found. They confirmed that only tire had excessive roadforce and replaced ONE tire, for a prorated fee of about $40 (Pure BS, the tires had about 1500-2000 miles on them). Unsurprisingly, the vibrations continued. I had the manager ride with me to confirm. He looked at the odometer and said, well you have like 270 thousand miles, so it could really be anything. I laughed out loud and told him everything was new; bushings, steering links, all 4 ball joints, all wheel bearings, rotors, wheels, calipers, driveshaft, etc. He said I don't know, but I can call Falken and see if they will just refund them and you can buy something else. Falken again said no.
I left and went to a Big Rig truck shop about 2 hours away and had them shave the tires round. Shockingly, the truck drove smooth as glass after that. The tech said they were pretty bad and showed me a pile of rubber that was cut off from the tires.
I got a whopping 23k miles out of the tires because I had to have them cut down to be round. I spent well over $1000 just on the tires, let alone several thousand in parts after repeatedly being told the tires were good.
After all that, I bought a set of LT285/70R17 Goodyear Duratracs. No issues with them and cost me less than the Falkens did after their ordeal. I spent $1009 on the DTs from Discount out the door. I always sweet talk them and ask if they can do a better deal, or take off fees. They always oblige.
Good luck.
