All 15" 1970 b-bodies had GOODYEAR POLYGLAS GT F60-15 RWL tires.

there is a change during the model year around November '69 production from "no-size" to "size" in RWL

Kelsey-Tire is the manufacturer & tire can be purchased thru a couple MOPARTS members - Rusty smallhurst & Jim 44D6PAKCUDA.