Noticeable, regular "lurch" felt on smooth roads.

[deserteagle71]

My rears will get a flat spot after a couple of weeks sitting. Makes no difference if they're fluid filled or not.
I road my tractor a bit, and the tires smooth out after a couple of miles.

^ Same with my John Deere. Lurches all over the place for the first few minutes of operation after it has been sitting for days. After that, smooths right out.

 

[kohog]

That is my first thought too. Pretty well every tractor I've used has at times developed a "flat spot" feel from having sat in one spot for long time. These large lubberly tires tend to do that way more noticeably than say an automotive tire. Since you had the tires swapped when the tractor was new, one wonders what the history of the AG tires was that your dealer put on for you.
This becomes a subjective thing BUT the dealer owes you a set of reasonably round tires that do not flop or thud on the road. He should ride it himself and give you an explanation OR a different set of tires. [I assume by now you are past the possibility that you had left it in 4WD while on dry road?]

Interesting point. However, if left sitting for a while and a flat spot does develop, would not that result in a "dip" instead of a lurch? I have to be careful with the words I use to describe what is happening here. The lurch throws the tractor momentarily "up" on LHS, not down. Also, tractor has 4 tires, how come just the one wheel is having this prblm? Dealer said to check a few more things and if prblm persists they'll dispatch a mechanic.