When you say siping, I'm assuming you're referring to cutting your treads for better tread clean-out due to tire flex.
If you're referring to siping that would be present in the OEM shape/tread pattern of the tire, I don't know why it wouldn't be a good idea, and I can't imagine it hurting anything.
__________________
"¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"
|