12.5 inch tires, "yida" seems to be the brand name.
My earlier research suggests that some bike tires have date codes, in the form of circles with an x in it, with either dots and or arrows. Does anybody know of a good site that has bicycle tire code dates?
A tire's speed rating is an indication, expressed as a letter code on the tire sidewall, of a speed the manufacturer expects the tire to be able to sustain over a long period of time without coming apart.
This is less about selling more expensive tires, although that ends up being the functional consequence, and more about fears of liability.
The “official line” that tire sellers generally get is, “Don't ever put on a lower speed rating than what was already on the car.” This, although good advice in general, has to be balanced against the car manufacturers' predilection for putting increasingly over-rated tires onto new cars.
It's hard to understate the importance of knowing what the speed ratings really mean.
If for example, the manufacturer did put V-rated tires on that minivan, it can be difficult to convince many tire places to put an H-rated on as a replacement.
The lowest speed rating you will probably ever see on a passenger car or truck tire is either S or T, which appear most often on dedicated snow tires.