I was thinking about the?480/400 x 8 / 7012?Tire & Tube Kit from Aircraft Spruce model 7012. Only $35 a set. They are about .4" wider than stock, but otherwise seem about perfect. They also have a sawtooth tread pattern if you like that.??
https://www.aircraftspruce.com/catalog/lgpages/roundribbedtire.php
Tom Yoder