The product is 243
27*9=243
27x9's would be good if you wanna be conservative, but if u wanna push it, you could get 28x10's, but you may need to flip your tie rods depending on the lugs on your tires. i have an o4 sportsman 500 on 28 in silverbacks with 2 in lift and spacers and i have ho clearance problems.
Multiples of 9 are numbers that can be divided by 9 without leaving a remainder. They follow a pattern of increasing by 9 each time. The first few multiples of 9 are 9, 18, 27, 36, 45, and so on. In general, the multiples of 9 can be represented as 9n, where n is a positive integer.