Select the rim with lasso tool, copy it on to a new layer. Right Click>Load Selection. Go Filter>Blur>Radial Blur set to Spin and Quality to Best. Now set the amount.(you might have to redo this stage few times until you find out what's highest amount without the wheel going messy.)
If you want to blur the tyre pattern allso, Do the same as above but instead of radial blur use motion blur.