35" tire question on these stock rims

[rugbymooch]

I've looked through lots of threads for this info, but gave up, please forgive me for starting a thread on it.
The trustworthy shop I use for all modifications says that this rim on the 392 can't handle a 35" tire, yet I see lots of pictures of them on 392s (even some 37"). They said I need rims at least 8" wide.
Now, I am looking for 12.50" tires. Am I missing something?
Looks like the tire manufacturers support his argument, yet some pictures show some of you are doing it.
This shop never upsells me, actually the opposite, so that's not a concern at all. But are they missing something? Anyone running 35", 12.50 wide tires on the stock rims?

 

[SmoothDriving479]

12.5 wide is pushing it on the stock wheels. It will probably wear a lot faster, and can be a hazard safety wise.

 

[RockAltered]

I run 61 lb. GY Dura Trac 315 70 17 in supposed weak D range on stock JLUR 7.5" wheels without lift or issues.. They are claimed 12.7" wide and 34.4" tall. I'd rather beat the sidewall than the wheels and plan the same for the 392 unless something new and better arrives. Life is a compromise.