Had to replace rims because -
 

Have any of you had to change your aluminum rims because of rim brake ware? If so how long did you ride before the rims wore out. Also, is there anything you can do to extend the life of the rims such as softer v-brake pads to save the rim and sacrifice the pads? I live in a very hilly area and I am on the brakes a lot. After a 8-9 mile ride I have to wipe off the brake pad dust from the fork and downtube. I also wipe down the rim surface and have a lot of residue. I have looked into converting the bike to disc brakes, should have gone that way from the start, but that is very cost prohibitive. Thanks in advance.
Frank.

I've gone thousands of miles on the same rims with no issues, I wouldn't worry about it. Kool Stop pads seem to be a popular choice.

How many miles were on your rims? My HED Belgium front rim (does more work braking) has maybe 26,000 miles on it with about 1.2 million feet of elevation gain. Doesn't appear to be anywhere close to worn out. I weigh about 205# too. I've used both Shimano and Kool Stop pads during this time.

Thank you both very much. You just saved me both concern and money.
Much appreciated, Frank.

Check your pads for anything they might have been picked up and that are stuck in the pad. For some reason my Bontrager rims that came stock with my FX seem to shed small metal shards from the rim to the pad. I can tell because every so often I'll get a metal on metal sounds from the brakes. A pair of tweezers or small blade usually does the trick removing them.

Good advice, I will check them out. Thanks.
Frank.

Found a very easy way to prevent rim wear from my v-brakes, don't use them. When going down hill on my ride today I decided to just let it be and see what happens. Other than the hill that required a 90* turn at the bottom I didn't have to use the brakes once except to stop and have a drink. Minimal wear on pads and rim.
I realize this is not a realistic fix and I am only half joking but if I do not use them then in fact there will be no wear to be concerned about.
Be safe all, Frank.

I recommend changing pads -- it's likely the pads and not the rims themselves. The Bontrager AT-750 rims seemed to shed a lot of aluminum bits into the stock Tektro pads, but dual compound Kool Stop pads cured that immediately.

^^ I am running Kool Stop black mountain bike pads and they are picking up the filings.