You can improve the ride on your Toyota by changing the aspect ratio of your tyres for something taller. You don't have to change the tyre width to do this - a quick look on blackcircles.com shows there is a decent choice of 205 16-inch tyres available with a 60 or 65 profile, which would help to improve the ride quality without having a narrower tyre which would slightly reduce the amount of grip available. It is also important to consider that this will also change the handling characteristics slightly, as the taller sidewall will deflect more during cornering. However, you may consider this a small price to pay for a better ride.