Super Swamper SSR

I have been looking for an answer for the last couple of days and have had no luck. I was originally looking at the 28x8.5x14 Super Swamper TSL's but they are not wide enough. I think I am going to go with the Super Swamper SSR's now and put them on a 7" wide wheel. My question is what makes the 27x9.5x14 dot approved and the 27x10x14 non dot aprroved? Also what offset wheel should I go with? I tried to call ATV outfitters today but they may still be closed for new years. I will try to call them again next week and get some pricing. Just want to have an idea on what wheels I want before I call. Also it says on the Interco site that these run 27.5 tall. Can anybody confirm that these run true to size? Thanks