Ag tires (R-1) are generally the preferred tire for usually dry land farming. Also known as “lug tires”, the R-1 has a traction grabbing component- the lugs themselves. They are typically angled at 45 degrees or 23 degrees, depending on the manufacturer.
Some areas around the world needed a more aggressive Ag tire- which is where the R-1W comes into play. It has 25% more tread depth than a typical R-1. These are more suitable in wet or moist soil types and heavy clay soils.
R-2 tires are an ag alternative that are less common in North American markets. The tread depth is twice that of a R-1 tire. This aggressiveness is apart of the specific design made convenient for farming in wet areas that can be mucky or pure mud. The R-2 is used predominantly in rice paddy or sugar cane applications.
Turf tires are considered to be R-3. Like the name states: these tires are suitable for general use, while offering the least amount of turf damage. Studies have shown some users even prefer the low, wide tread design with lots of ground contact on slopes and in snowy conditions.
A compromise tire that is common these days is the industrial R-4 tread design. Industrial tires offer much of the traction advantages of a lug design while having less of a negative impact on turf.