Those are nice-looking rigs. I agree, 35’s look great on a 5th gen and thin 35’s also seem to be the upper limit for our clamshell front ends/front suspension. 37’s-40’s are amazing at popping front end gears, non-rcv axles or diff housings. (Our rear 8.2 axles seem pretty bombproof. Haven’t heard of one breaking yet)

For your research, I took a poll of drivetrain strength on the toyota-4runner 5th gen  forum:

https://www.toyota-4runner.org/5th-gen-t4rs/304407-offroad-drivetrain-durability-tire-size-increases.html

Small data sample size but overwhelmingly folks run 31’s- 33’s without issue. 34-35’s next, with a few issues reported, with very few running 37+ on the forum and not many responses about durability.

What i see about 35”+, is on youtube of some big 5th gens and they break front end parts fairly regularly. For me, 285/75-17’s or 34’s are the biggest tire i’d feel like i could safely run without something in the front end ending up the fuse on each (or every other tough trail ride)