Henro,
My "bar" tires are definately R1. I have "turf" tires too, that are R3. R4 tires are "industrial" tires with more rigid sidewalls and flatter, less agressive bar tread patterns than the R1s. The unanswered question at this point is whether there is a different class of tire called "ag" or "agricultural" that is different than the "bar" tires. It could just be a matter of semantics and a dealer or two wanting to remind me that they knew more than me about the tractors options.
I did some reading about the load ratings of tires awhile back and understand a little about the "ply ratings" but wouldn't claim to be an expert. For example, the 210 loader on the 2210 is spec'd for use with R1 4PR or R3 4PR tires and can be used with a higher "PR" (ply rating) but not a lower PR. You can buy turfs, bars, or industrial tires with a variety of ply ratings. Of course, the higher the rating the higher the price, typically.
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