Self propelled swather tires

I need to replace the tires on the hw340, dry rot and cracks on a turf type Titan 18.4/26. I do have plenty of hills and there have been some white knuckle rides off wet slopes. What's the opinion of bar type tires on these machines? Are there any scrap yards that I could buy mounted tires off junked machines? I would imagine this is too small for any modern combines to run.

Self propelled swather tires