R/T means "rough terrain" or "rugged terrain".
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...Is the alphabet soup known appropriately as the LT tire market big enough for another letter? Until recently, there were only three types of LT-sized tires: H/T for highway-terrain, A/T for all-terrain and M/T for mud-terrain.
Now there may be the makings of an R/T, or rugged-terrain, tire, although the U.S. Tire Manufacturers Association (USTMA) does not yet acknowledge or track such a tire segment. But light truck tire manufacturers and marketers confirm consumers want a tire that fits in-between the A/T and M/T tire segments.
Nitto (Ridge Grappler), Toyo Tire U.S.A. Corp. (Open Country R/T), American Kenda Rubber Industrial Co. Ltd. (Klever R/T), Omni United USA (Renegade RT+) and Atturo Tire Corp. are actively marketing R/T or hybrid-terrain tires. Atturo uses another letter, "X," in the nomenclature for its Trail Blade X/T.
The Nitto enthusiasts were demanding… a product that has the characteristics of an A/T tire — i.e., comfort, low noise — but wanted a more aggressive design like an M/T tire to match the strong persona of their full-size pickup truck...
https://www.moderntiredealer.com/article/731961/r-t-tires-new-category-not-marketing-hype
Quote
...Is the alphabet soup known appropriately as the LT tire market big enough for another letter? Until recently, there were only three types of LT-sized tires: H/T for highway-terrain, A/T for all-terrain and M/T for mud-terrain.
Now there may be the makings of an R/T, or rugged-terrain, tire, although the U.S. Tire Manufacturers Association (USTMA) does not yet acknowledge or track such a tire segment. But light truck tire manufacturers and marketers confirm consumers want a tire that fits in-between the A/T and M/T tire segments.
Nitto (Ridge Grappler), Toyo Tire U.S.A. Corp. (Open Country R/T), American Kenda Rubber Industrial Co. Ltd. (Klever R/T), Omni United USA (Renegade RT+) and Atturo Tire Corp. are actively marketing R/T or hybrid-terrain tires. Atturo uses another letter, "X," in the nomenclature for its Trail Blade X/T.
The Nitto enthusiasts were demanding… a product that has the characteristics of an A/T tire — i.e., comfort, low noise — but wanted a more aggressive design like an M/T tire to match the strong persona of their full-size pickup truck...
https://www.moderntiredealer.com/article/731961/r-t-tires-new-category-not-marketing-hype