... I think the weight on the front versus back is something like 40/60...hence the back wears much faster than the front.
I've thought of that, and while I think weight distribution is a factor, I don't think it's the only one, and likely not the biggest one. The main one, I think, is that the back wheel is used to drive the bike forward. Friction between the tire and the road is what allows the bike to advance. The front wheel, by contrast, just passively rolls along. The other issue is braking. While the front wheel gives more stopping power, I often use the rear wheel first or more strongly so as not to pitchpole the bike.
Thanks, DaveB and JDFlood! You've confirmed what I suspected, but I didn't want to replace the rear wheel only to have the front suddenly prove in need of it, too.