They do pretty much look the same but the 555streets have twice as many tred lines, and have deep tread. Also made of a harder rubber compound.
Yea, those are AFS 9" that my 275 are mounted on. Widening the rims would be a very big waste of money, and the shop would really have to know what they are doing.
When I got my rims from AFS about 4 years ago, they were on sale for $500 a set. Thats only $125 a rim. They also gave me free shipping at the time.
Here is a pic of the 555streets so you can see the diffence between the two.