Saw those nankang AR-1 on ebay for around 200 each for a 265/35/18. interested to see how they perform. Definitely worth a go. If I was in the market for a semi id try it. Keep us posted if you try them hrd-hr30.
I wouldn't, unless you can see something very wrong when you take the head off. These engines are very strong, even with high mileage. The compression in yours seems ok.