The Standard 77 &amp;amp; 88 carried a 26 inch diameter whereas the 66 carried a 24 inch diameter. The row crops carried the following 66 38 inch 8-38,9-38,10-38 the 77 38inch 10-38,11-38,12-38 the 88 11-38,12-38, 13-38. I am not sure how many with sizes were available for the standard but I think 8,9 and 10 were available with different lug types.