Hi, I and allmost everyone else driving built trucks here in our country, Finland in Europe, have a big problem. They do not allow us to put bigger tires than the biggest optional tire + 2" . I for instance have a K20 made 1981 and the stock tire is 9.50R16.5 If I put 33" under it and drive it on public roads I may get a ticket. If I get the ticket 3 times in 1 years time they take my drivers licens away for a few weeks . If any of you have some kind of document or other proof of optional tires offered in 1973-1988(91) I and all the others driving Chevys/GMC's K5/K10/K15/K20/K25/K30/K35 Blazers, Jimmys, Suburbans would be very happy .