It very much depends on how you drive your RAV4.  Tires are always an
exercise in tradeoffs; for example, harder rubber compounds last a
long time, but tend to be noisy and provide worse traction than 
softer rubber compounds that don't last as long.  Tires are also
designed for different environments.  Tires with aggressive tread
designs are better in snow and ice, but generate more road noise.
Others with less aggressive treads are better on dry pavement and 
are quiet, but are bad, even dangerous, in the snow.

Most people replace their worn tires with a type similar to what is 
shipped on their RAV4 - all-season tires.  These tires are a general
compromise between most normal driving conditions.  They are adequate
for all of them, but excel in none of them.  They have a moderately
aggressively tread pattern that is good in rain and snow, but it not
excessively noisy.  They are designed to last for 40,000 to 60,000 
miles under normal use.  With the Full-Time 4WD that most RAV4s have,
these tire are all that most people will ever need.

Some people who live in the "snow belt" maintain 2 sets of tires, 
often on separate wheels; one set of tires that are designed for
good performance on wet and dry surfaces, and one set that are for
winter driving exclusively.  The wet/dry tires provide better
performance and tire life, while the winter tires are excellent 
for snow and ice conditions.  This helps eliminate many of the
compromises of all-season tires at the cost of an extra set of 
tires and the inconvenience of installing them each winter.

Still others do extensive off-road driving.  They require special
tires for this purpose that maintain traction in sand, mud, and
other harsh conditions.  They may install these tires only when
they plan to drive off-road.