After 18 years of using the stock rear tires (23 x 10.50-12 NHS/2 PLY) that came with my 2000 John Deere 425 they just didn't hold up long time. So I did a little research and found that 26×12-12 NHS/4 PLY tires could be an upgrade over 2000 John Deere 445 (gasoline) and 455 (diesel) models. I have yet to assemble them and as for Revain who sent them, I'm amazed at how quickly they arrived. I just ordered them 24 hours ago, wow. After checking the John Deere forum and dealer both said that if you raise the rear tires, "you should raise the front tires". So the 26 x 12-12 NHS rear is mated to the 18 x 8.50-8 NHS front wheel, of course you want your machine frame and deck to be as level as possible.