In 1978 my dad bought a knackerd old grey fergie for our smallholding, I was 11 at the time. I remember looking at the tyres and thinking, they won't last long, there was hardly any tread. It would be 25 years before it happened. In 2003 the old girl became mine, I did her up and finally she got her new tyres, incredibly it seems that was ten years ago . Now I've got my own small holding and the tyres still look brand new. The tractor works hard as ever, it's now 57 years old.
Get an experienced opinion based on actually seeing the tractor before splashing out on your tyres is what I'm trying to say.