How long should running shoes last?

You should not need to break in running shoes.  If you think they are causing blisters, you need to get a better fit.

As for life span, there are several factors.  I replace my shoes after 3-4 months, even though my mileage is relatively low. But as soon as I see some wear on the heel, I know I am getting less support. The age alone is said to cause some breakdown in the support.  Mileage, it's usually recomended to change after 200-300 miles.  Another trick is to get a second pair a couple or three months after the first, and periodically compare the "bounce" between the old and the new pairs.  When you can tell a difference, the old pair becomes used more for day to day use, not running. (I assume you save the running shoes for running.  Training and racing only, not going to the mall, or doing the yard work, or whatever.  Until they are retired).

I disagree with this a bit - I've found that I'll get a small blister or two when I change shoes or models. Nothing major and nothing that will keep me from training.

And to answer the OP's question:  It seems most people say 300 miles, but others go as high as 500 or as low as 150.  Like gearboy said though - look at the wear on the treads and compression/collapse of the sole.

Bruce.

Wow, 300 miles.  I had no idea it would be so low.  Good thing I asked!

Thanks guys. 

When I was in the Army and younger:  6 months

Today:  3-4 months. 

The type of shoe and where you use it has just as much to do with how long it lasts as you do.  For example, in college we were given a set of adidas running shoes w/ a blown carbon sole it was a soft shoe and was great for track workouts. Being a 400M runner I liked the shoe, until I destroyed the sole in 2-3 weeks and it was completely bald in the forefoot. less than 30 miles.

Most of the higher end training shoes have a carbon rubber sole that is firmer but lasts longer when used on the roads. Depending on your weight you may need to replace you shoes more often. Personally at 200+Lbs I change them every 3 months and the padding is just about dead. I wear thru the padding in the shoe before I wear down the sole. You maywant to  check your shoes by removing the insole, feel where your forefoot is and heel, then inspect the same areas within your runnign shoe and see how much padding is left between you shoe and the road. 

As a rule of thumb I listen to my shins and knees when they get a little sore from a long run I change them out. 

Tod

I am a marathon runner, that's my background.  I usually used two pairs for training for a marathon, ASIC Kayano for the long runs and ASIC DS trainer and use both for training and race day; I usually train for 4 months before any marathon and the mileage would be around 400 miles maximum; would not use them after than.  I would buy a new pair every 350 to 400 miles.

Most long distance runners when we find a shoe that they feel comfortable with, what we usually do is buy 4 or 5 pairs of the same model so no to upset training.

If you buy a new pair, use your short mileage to break them in.

Hope the above is helpful