Need help with LST tire info

[notnodak]

I'm planning on running LST2 ATX tires on dish wheels when I get my 9xl motor this week and was looking at gearing. I'm trying to use the top speed calculator and need to know the ATX's diameter and what # to use for balloning. I think it's 7" and .25" ballon but I really am guessing on this.
Anyone know what the diameter and ballooning is for these tires.