changing backup tmp location

I'm trying to backup my virtual servers to a remote site, but my /tmp partition is too small to create the tar's. I set it up as only 1GB in size and don't really want to change that or make it part of my root partition. Where can I change the default location virtualmin uses to tar the backups to? The default appears to be /tmp/.webmin/.

Sorry if I missed this on another thread, I looked around but only found incomplete threads.

Thanks much!