No I did not know. I assumed that the UTQG ratings were for all brands. Thanks for clarifying.
UTQC ratings are simply how each manufacturer determines how well their tires rate within their product line. So Hoosier, who makes racing tires, could rate their Pro-Street at 500 because of how long it lasts compared to a race tire, yet its actual on the street mileage could be more like a 200 compared to someone like Mastercraft that make high mileage tires. So yea, its a tool for use within a single manufacturer, not across manufacturers.
The Pro Streets look like they would be a cool street tire, but their compound is a bit hard and they are designed with way too much sidewall to be a serious handling tire. Primary market these were developed for was the street rod crowd, not the street handling crowd.
There are a lot of 15" drag race oriented tires with soft compounds and soft sidewalls. There are no serious UHP, handling tires in 15". The closest thing to this would be Avon CRZZ, which is actually a d.o.t. race tire and they do not recommend it for actual street use. Soft compound, stiff sidewall, $350+ per tire.