Got new tires and..

[R1campr]

I bought our Cherokee grey wolf 25 rr in may of this year. The tires were trail express 205 75d 14's dated 12 20. No spare so I bought one using the numbers on the tires and for wheel, using the numbers on the sticker on the trailer, 14x6.
One of the tires has a few splits in it, they don't look like cuts or dry rot cracks. All the tires have what looks to me like an inverted welt going around the whole side wall half way from the rim and tread, they are about a quarter inch wide. I don't know if that's normal, but I am replacing all the tires anyways, To Goodyear marathons 205 75r14.
I go to take the wheels off one side and find out the wheels are actually 14x5.5. Is that gonna be a problem if I have to use my spare which is 14 x6? Why would FR put the 14x5.5 wheels on and have a sticker that says 14x6?
So then I measure the frame to hub distance on one side cause it looked funny to me even after parking it going strait. The rear axle is a quarter inch farther to the passenger side than the front axle, (it's tandem axle).could that be a problem tracking? I haven't measured from the tongue yet to see what the alignment is.

Seems like the further I go, the more stuff I find wrong. Not sure if I want to even measure for alignment. We like the camper anyways, only other problem yet is the water pump inline filter was loose sucking air instead of pumping water.

[Tireman9]

Not sure if you read or typed the date code correctly. If the last 4 digits of the DOT serial were in fact 1220 you have tires manufactured in the 12th week of 2020 which is quite a trick.

Could it be 2012 which would be 2oth week of 2012 ?

This web site has good info and is from a fellow tire engineer

[R1campr]

Whoops, 2012 I hope the future tires are better than nowadays