i have 40's on my toy! so no 38's arent too big. But if you have stock axle shafts you will break them with 38's in no time! So upgrading to Longfields is a must. And you need to be more specific with your spring height question. Are you wanting to know what size spring you need to run 38's?
I guess that would be the right way to ask that.
What sring do i need to run 38's?