Well, on mine it's the passenger side.

Unfortunately, I have directional tires installed so both passenger side tires are showing significantly more wear than the driver side tires.

At some point I will have to swap them and I will have to incur the mounting balancing cost.

I won't ever buy directional tires again.

Way too much hassle.

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1993 W124 300D
-297K on the clock as I type this.