Rikens are supposed to be made my Michelin. At least, that's what I've always heard. Pretty sure it was at least true at one time, but no idea if they still are.
I wouldn't necessarily call crappy tires 'unsafe.' I'd rather someone have them than a bald name brand...for me, the biggest concern is wet performance, and cheap tires do often shed water pretty well due to simple tread patterns with giant tread grooves.
Used to be, when I thought of house brand tires, I thought of generic designs like this:
Those are Dayton Quadras, which were the lowest-end thing Firestone carried. They were S-rated tires generally made for econocars or older domestics with 14-15" wheels. The sidewalls were about as stiff as butter and they didn't last terribly long. But they seemed to grip decently enough, as far as a generic cheap all-season tire was concerned.
If you had something bigger than 16's on your car, however, you paid up for something better because you had no other choice.
Now, cars are rolling out of tire shops on 17-18"+ wheels sporting this kind of trash:
And that shit scares me. Those are terrible, awful tires with bad tread design, bad compound, bad everything. In general, cheapo summer tires have become way too prevalent around here...not to start 'yet another snow driving debate,' but having tires that, at low temperatures, might as well be smooth pieces of hard plastic...that's not something that's helping the stereotype of southerners not being able to drive.
And at any temperature, they serve to enhance my biggest complaint with the newer trends toward big wheels on everything...short, stiff sidewalls enhance responsiveness, yeah, but overall grip seems a lot more dependent on having a decent tire. While these tires might be a +1 in responsiveness, they're a -20 in not breaking traction in a sudden, unexpected manner.