I've got a 255/50/20 tire on a 2013 Ford Explorer Sport with sidewall damage as shown. The damaged area is about 1" long and the damage is about 3/32" deep. Does it need to be replaced? The tires themselves have 8/32" of tread depth remaining so their fairly new yet. Thoughts?
Yes.. It needs to be replaced as it is not safe. It would also fail an MOT like that.
It might not fail today or even next month etc, but you couldn't trust that tyre. Under heavy loads like cornering, braking or at speed etc that tyre already has a real weak point, and failure under those conditions could easily end in disaster. Its not worth it.
The MOT test in the UK is an annual test on vehicles that are aged 3 years or more. In other countries this test may be understood differently e.g...vehicle inspection, saftey & emissions inspection, roadworthiness inspection etc etc. Test in other countries may also have differing time intervals.
Disclaimer: Your safety and the safety of your passengers is paramount. If you have any concerns about this I would err on the side of caution and have the tyre replaced. If it was to fail, resulting in an accident and death: "it should have been ok" wont bring someone back.
However: Looking at your photo it seems very close to the bead, which is a comparitively strong part of the tyre as it has a steel wire in it and is not subjected to loads as high as mid sidewall.
If it hasnt deformed (bulged) it may be ok. If you must keep it temporarily, i would move it to a rear wheel. If it is going to fail id prefer it to be on a rear wheel than a front.
If you have a spare wheel the same, I would swap it and keep it as a spare.
I would highly reccomend that you take it to a tyre shop and have it inspected by a experienced professional.