the newer, softer compound dunlops do wear faster. the sp 5000's, for example, will barely get you 30k from what i hear, but that's if you rotate them. tires on the driven wheels will always wear out a lot faster so i guess your tire wear is just about normal if you insist on not rotating them.
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"