The SSR is one branch of an entire line of TSL Interco tires including; Super Swamper TSL (bias ply), Super Swamper Radial TSL, Super Swamper TSL/SX, Special Service Super Swamper TSL, Super Swamper TSL/SSR, TSL Thornbird Bias ply, and the TSL Bogger. TSL
The image linked below shows the sidewall of an SSR and it, just like the OP's original post, clearly says "TSL" not "SSR".
If it makes you feel better, YOU WERE RIGHT in that his tires are SSRs. You were wrong in telling him that they were not TSLs.