Well, I do have a spreadsheet somewhere with suitable dimensions for everything from 15 to 20". IŽll see if I find it and list suitable sizes and how much off they are from the original 225/60ZR15s. However 8" would mean at least 205 width. And 9" would be 235 (225 might be cutting it too close). I guess most guys (and gals) here go with 255 and 275 in rear...