Re: Vibration at 68 to 73 mph
First off, I bought my Wk2 as a program vehicle so it had ~20K on the clock upon delivery. My vibration issue was strictly a tire balance issue. Simply rotating the tire 180 on the wheel won't solve it. Normal balancing only reduces the "static" harmonics from the tire/wheel assembly. Match mount balancing can help you fine tune the mating of the tire/wheel assembly in an attempt to lower the static imbalance that of the assembly. Road force balancing will actually determine how much "force" a tire exerts onto the road surface. The greater the static/road force values, the deeper it can travel through the chassis. You could have a perfect static balance and say 35lbs of road force on just one tire and you would definately notice a vibration in our Wk2's regardless if you are running on 18's or 20's. On another note, just because the machine says the asembly is within limits doesn't mean it is. Balance machines require regular calibration for them to produce satisfactory results.
With the factory 18's Latitudes (these are junk IMO), I had this exact vibration. I travel the same stretch of road everyday. First I verified the static balance was within limits and it was. Next, I checked road force and I had 3 tires that had over 35lbs of road force and one tire with 12lb of road force. Once we hit the first one with high RFV, it visibly was shaking the safety hood and the monitor attached to the balancer! Immediately snatched the Latties off and installed MS2's. Right off the bat, I had two of the brand new MS2's with over 38lb of road force. Finally got a full set with extremely low force values (under 30lbs total!) for the whole set which is very rare even for Michelin. After all this crap and spending countless hours on the balance machine, my Jeep finally rides like I would expect it should. The last thing was dialing in the air pressure. On these vehicles, only a few PSI can make a difference in comfort.
I will say that I love road feel in any vehicle, but I think that the engineers went a bit overboard on some of the rigidity of the suspension on our Wk2's. For starters, the caster angle is very high/ positive for a suv. Whenever I can get some spare time, I'm going to take some of the caster out of the front and see if I can make the steering a lil less sensitive. I'm still waiting for another Wk2 to come in with ride quality complaints so I can experiment with steering angles first.