I do not see an issue with the rim width, a few years ago I converted my 2.5 ton Reo off 9.00 x20's onto 11.00 x 20's again due to the rarety of the 9.00's, understandably anything bigger may be difficult to get onto the rim. Fortunatly the Reo has adjustable steering stops, I had to adjust these out fractionally. Does the K9 have adjustable stops ?
The added increase in rolling radius also gives higher gearing which helps reduce engine speed when cruising.