Tier Ratings

The engine tier depends on the model year and horsepower rating of the engine. You will need the engine manufacturer, model year, and family name to determine the tier rating for the engine. 

Off-Road certification database and Executive Orders (EO).

As of January 1, 2011, engine manufacturers are required to produce engines certified to the following levels:

Engines rated 50 to 74 bhp: Interim Tier 4.

Engines rated 75 to 174 bhp: Tier 3.

Engines rated 175 bhp and over: Interim Tier 4.

Off-Road Compression-Ignition (Diesel) Engine Tiers (PDF)(ARB chart in PDF format)