All interesting theories indeed but it still appears that there is no definitive resolution.
Here's an excerpt from one of my previous posts:
I can feel the vibration in my seat & I can see the psngr seat wobble anywhere from 45-60.
Here's the latest:
I refuse to go back to the incompetent dealer that screwed up the balance & damaged my truck, that's another thread, so I visited 2 other tire shops:
> The first did only a static balance with clip on weights on the inside lip; better but still not like before & vibration was most noticeable when towing.
> The second shop, a national chain, spun the tires, removed all the weights & spun again performing a Dynamic balance with clip ons on the inner lip & stick ons on the inner hub; again better but still vibration.
I have read other complaints abt the stocker Goodyears but I know an unbalanced tire when I feel it. What puzzles me though is the front tires seem fine as I feel nothing in the steering wheel and the dealer that screwed it up to begin with did the balance???
Latest: I have since upgraded to 20x8.5 Granite Alloy wheels with BFG Gen II KDW 285/55's. They were purchased as a set from The Tire Rack. The ride is much better but I can still feel a little vibration in the seat; it only seems to be around 50 & seems to go away once the tires are heated up. I also noticed these wheels have a lot of weight on them. Having sd that I must tell you I'm a perfectionist and this is my first time owning a full size truck so maybe I'm expecting to much. After all it's not a Caddy

.
What about owners with dropped Titan's, aftermarket shocks etc. that had the wobble? Any diff?
Since I had the white ltrs turned inside around 400 miles I can't say for sure if this was an issue from day one. However, I didn't notice it until the dealer rebalanced the tires; def stood out then.
Just for the record I owned a '93 Toyota truck (year before they dubbed it Tacoma) and I had the "Death Wobble" but only above 60. When I purchased the truck the owner had installed Ford Ranger wheels with oversize tires and I thought they just needed a good balance. Well had it done numerous times to no avail. I then purchased new wheels & tires from Discount Tire Direct and low & behold the same issue but only above 60. Visited several shops and got several opinions from "it's the tires" to "you need hub centric rings". Sold the truck so I never figured out exactly what the problem was.
__________________
Rob
'06 SeaDoo RXP - Stg I+
'93 Stroker Mustang GT - "10"
'07 Titan - CAI, Exhaust, UpRev, etc.
"Don't dwell on the past, it will become your future"