I may have been mistaken about an R4 tire being 4 ply but from what I can find the R14 is a 6 ply tire
https://www.prioritytire.com/goodyear-r14t-15-19-5-129a8-6-ply-as-a-s-all-season-tire/
https://www.moderntiredealer.com/articles/20065-goodyear-r14-farm-tire-is-the-answer-for-kubota