Tire for KFX 450r
 

Hi,
I am trying to find 21X10X10 dirt tires for the Kawasaki KFX 450r. My goal is too increase top speed a little bit by increasing my tire height. Does anyone know who make such a size?
Secoundly it was brought to my attention that atv tires have " speed ratings". I didn't know this. I am concerned becasue I have changed my sprockets to 15 front and 323 rear. I have about 11 miles an hour more than the original the stock kawasaki. I wonder if the stock dunlop are rated for these speeds? Does anyone know anything about this.

thankx