Ok...I dug up this old chart but it seems pretty consistant with what I said earlier,except it goes much lower and higher and
COMPOUND DUROMETER HARDNESS WEAR RATE
Silver 25 Soft/Medium Moderate
Platinum 25 Soft/Medium Very good
White 26 Medium/Soft Good
Green 29 Medium Good
Gray 31 Medium Moderate
Pink 34 Medium Moderate
Blue 36 Firm Moderate
Purple 42 Medium Excellent
Red 54 Firm Excellent
2Blue 55 Firm Excellent