Something doesn't seem right here. Maybe you've upped your bit rate or something? I don't know exactly what you're doing, but for collaboration, if the tracks are all just mixed later, you could share mp3's to listen to while recording everything in lossless wav files?
Maybe this helps a little (scavenged from a Reaper forum somewhere):
If you know the bitrate, you can estimate file size with the following formula: File Size in MB = (Bitrate in kbps x Playing Time in minutes) / 140
The bitrate for CD audio (44.1kHz, 16-bit, stereo) is 1411 kbps, which you can easily calculate (44.1 x 16 x 2).
The bitrate for lossy compression (MP3, AAC, etc.) depends on the compression setting, but you can reduce the bitrate (and file size) to about 1/5th of the original with excellent quality. With a high-quality MP3 or AAC file, most music will sound identical to the original in blind listening tests. (If you compress too much, the quality loss becomes more noticeable.)
With lossless compression (FLAC or ALAC), you can compress the file to about 60% of it's original size with no quality loss. (When uncompressed, the bytes are identical to the original... like a ZIP file for audio.)