Would you replace these tires.

I would replace them. With chunks coming out now they will just keep getting worse fast. And will blow out before you knw it

 

The 2nd pic looks like a bald spot. Less than 4/32 it comes off.

 

Steers I wouldn't screw around waiting on a failure. Change them.

 

Looks like the front steers on mine.
I replaced the front wheel bearing (it was the problem)and then replaced the steers and got a alignment.

 

I'd get it scheduled for tires, suspension/steering inspection and full alignment. The second picture looks like it's got some secondary rubber showing, meaning it's getting thin. It also looks like it's cupping, so if you don't have a shimmy or vibration, you probably will soon. Looks like that tire is running a little toed in because it looks tapered (more tread on the inside) and possibly has something else wrong to cause cupping.

 

Are those yokahma tires? It probably doesn't matter, but I bought a set for my car. Best tires I ever bought. Yoka has a big plant in Mississippi, so I think/hope they are American made. Chunks missing don't bother me, but maybe they should. If the tractor tracks a straight line, I would probably run 'em, but keep watching and gauging them.

Re-read your post: Wheel hop? maybe they need replace, then.

 

It also could be shocks.

 

I'd only replace them if you care about living and not crashing, otherwise they are fine. You need an alignment, and have your shocks and wheel bearings checked as well.
I call those " May pops." Because they may pop at anytime.