When you are buying new you should get new weather you seen at the dealer or not it should be new and if they dont correct the problem they are not a reputable dealer and I wouldnt go near him again , well maybe to serve papers for small claims court.
I grew up with "Let the buyer be ware". And feel it's the only right way.
Who will look after you if you don't?
Think about.
The tractor is "new" The tires are (must be?) original equipment so they can't be "old" or used. The sidewall cracking is a tire manufacture issue. The DEALER can't change that. If they were not showing cracking on the lot, they would have in a very short time anyway. (Again, tire maker's issue, not the dealers)
If you would have pointed out the defect to the dealer, you might have negotiated different terms on your purchase. Now, You feel slighted because YOU assumed something that was evident to anyone who would look. But,,,you didn't look, You assumed. And now you are upset.
Unless the dealer is a bigger person than you, both of you are going to be pissed at one another.
Great
Enjoy your tractor. Is the paint faded too? Or any of the plastic showing the effects of time and exposure?
By the way, Unless those tires are cheap asian "specials", sidewall cracking like that will mean nothing even after 20 years. The set on the Fordson are all cracked and checked, been that way for over 30 years. They don't seem to suffer from it, and I don't fret. It's going to be something sharpe pushed through the center of the tread that causes these tires to fail, Not blemished sidewall covering that is entirely cosmetic anyway.
I would talk to the dealer about the tires. Maybe he will give you a ten year pro-rated replacement warrantee on any failure due to the defect. (service call included) That would be a fine gesture that would cover your concerns and NOT kill a useful relationship.
I do check fluids lubes and fasteners. It's a mistake not to! Those guys at the factory are just working there.
I wish you well.
Cheers