Maxxis is the brand name Cheng Shin is using to make inroads into the performance market for many different types of tires. Their sponsorship and involvement in bicycle racing has made them a major player; especially in the mountain bike relm.
Where did you find the speed rating? I couldn't find it on the Maxxis website. Discount tire shows a smaller rim size of the Maxxis M8008 as being R rated (that's 106mph, not under 17 requires a parent
).
I also found it interesting that for N rateds tires the "common use" listed is temporary spare. And trailer tires don't even rate that high
Boy, that tread pattern sure looks familiar, Sigma Towmax maybe???
http://www.tbcprivatebrands.com/sigma/
-Bernie