http://www.croplife.com/equipment/john-deere-launches-final-tier-4stage-iv...
Mar 2, 2012 ... Final Tier 4/Stage IV regulations for off-highway diesel engines begin as early as
2013 for engines 55 kW (74 hp) and below. Regulatory dates ...
2012 Commodity Classic: Optimism Abounds | CropLife
http://www.croplife.com/management/2012-commodity-classic-optimism-abounds/
Apr 1, 2012 ... At the show, the company took the opportunity to announces the launch of its final
Tier 4/Stage IV regulations for off-highway diesel engines.