RL has various meanings in the Transportation category. Discover the full forms, definitions, and usage contexts of RL in Transportation.
Top recommended engine RPM. If a tachometer is used, it will have a mark (red line) indicating maximum rpm. Some tachometers mark the red line with a colored sector. Others have two lines: the lower one marking the maximum allowable sustained engine rpm, the higher line indicating the absolute maximum rpm. (RL) Tires with a red concentric line which were marketed in the late '60s and early 70s.
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