Tire Question

I usually try to find one with as close to the same height as possible. There are different size low-pro sizes, be sure and match them up number wise. Brand / casing would be nice to match, but very hard. Tread match ? The closer the better, but no huge problem. If it were me, i would probably run what you already have, if legal looking. Leave tire # 8 on there for now, save the money towards a new set. Maybe 4 at the time ?

 

Do not wait to replace that cupped tire the cupping will keep getting worst very quickly and they wear out very quickly. start checking at all your stops and tire dealers for a tire that is the same height and same brand would be a plus.

 

It's not good to run any tire cupped that badly on the tractor. I'd swap it out asap, as terryt said.
Match tire height as close as possible, and if it's not close enough, I'd move on to the next dealers batch.
I assume your 7 rears have a "lug tread", so no sense having a badly cupped highway steer tread if it ends up being on a drive/traction set, especially in winter.

Plus, give those front end parts a quick check, asap. It's a simple check if you can grab an assistant.
Just have them shake the steering wheel back & forth repetitiously, while you look at each linkage joint,
checking for (looking for) play and slop in the movement between the two pieces. Start with your pitman arm, and on down the line.