I sometimes get an email is this normal life from the my rim. Well there no simple answer.

Rim brake rims in the 450g to 500g range have a 1.4mm thick brake track approximatley. There are slme heavier rim with thicker tracks.

Aluminium is only so hard. Yes some brands of rims like hed have used a hard alloy. Borg rims are not as hard as those but  mid pack ( or better). Similar in fact to higher end DT Swiss rims. Some cheaper rims use softer metal.

The material hardness will have an inpact on rim life but its not big.

Much more important is

• the brake pad you use
• Brake setup/brake condition (the caliper arms should close with equal force and pads should be equidistant from the rim)
• Terrain (hilly routes tend to be harder on rims)
• Urban or country side use (urban roads are cleaner). 
• Braking style
• How often brake pads are picked clean.

Terrain is the obvious thing. Those hilly narrow lanes covered in muck will kill any rim. Where as flat fen land roads where you rarely brake help rims last. 

Urban riders can suffer from.brake wear if they stop start alot but in general urban riders tend to have cleaner roads.

Sadly the country roads are spending more and more time covered in muck and the weather is getting wetter and wetter.  Add the poor state of most roads is leaving more debris to be picked up by brake pads. 

That leads to the pads. Softer pads like aztec and Koolstop salmons so help rims last a bit longer but they are not magic bullets.

How you brake is also a factor. DraggIng the brake is going to wear rims nicely. Whereas firm burst braking can help dislodge stuff stuck in the pads and therefore rim life is extended.

Now the rim should be replaced at 1mm thick. It safe there but let it wear down to 0.7mm thick and your in the danger zone. This is easily measured but if it very concave get concerned.

Now how many miles this takes can be as little as 2000 miles or as many as 20000 miles for alloy rims.

Carbon rims can last alot longer. 30000km is not unusal from carbon rims. They can last longer than that. 

 All our wheels can be re rimmed though. Spokes can often be resused. So it a labour charge and a new rim and nipples. If hub bearings need attention then we can do that as well.