Well, keep in mind that tires sold in the US are also made to US DOT specs, and that you also pay for the brand name. Up here in Anchorage you pay quite a bit for the BFG and Goodyear brand names.
I'd look at the sidewall and check out how many sidewall and tread belts the Yokohamas have, and compare that to the BFG. There may also be a "treadwear rating" on the tire as well--something in the 400 to 600 range, and you may want to compare that as well.
For what it's worth, I've had Yokohama tires before and they were pretty good. Granted, they were 245/50ZR14 and mounted on my 5. 0L HO Mercury Capri. I never had any flats, and they handled 150MPH just fine. I have no experience with their light truck tires though.
Mike