Those two sources can help. Keep this is mind: Tempe is not uniform. There are wealthy areas in south tempe and around the tempe town lake, and some, well, down in the heel parts of town as well. A mile one way or the other could make a big difference to how your neighborhood feels.
I live in a family neighborhood near Southern and McClintock. Bigger homes, bigger yards, mostly built in the mid 60's to early 70's. It is a mixture of families and college rentals. I walk my dogs at night or to go to coffee shops all the time and have never had or seen a problem.

Here is one great resource which you can explore
http://www.tempe.gov/cau/
and here you can search by zip code
http://www.azcentral.com/CrimeMaps/

Joni -

Here is a website which should be helpful. Tempe as a whole is very desirable and has many amenities. I grew up in Tempe & lived near & attended ASU and never experienced any problems.

This site will allow you to search by zip code.
http://www.tempe.gov/cau/

Tammy