Do spacers affect handling?

any wheel and tyre shop should be able to take the wheel off to see if it were buckled or warped...
and your tyre wear can be a good indication
i'd have them all checked...
shouldn't cost much at all for that peace of mind...
 
Sometimes there can be a manufacturing defect with a tyre, meaning that you'll get an increased vibrations. Not only that you may of damaged the tyre and clipped a pothole, so make sure the tyre is still in good shape, not only externally but also internally as the the wire cords can break free.
 
Cheers. Well everything feels fine now by switching them so I'll see how it progresses. Will avoid the rainsports in future.
 
http://www.tyrereviews.co.uk/Tyre/Uniroyal/Rainsport-2.htm

ok, i've just read this...
though, the 1st review (at the bottom of the page) sounds pretty similar to what you described...???

Similar, but I would have thought they would improve with a bit of wear. Mine are rainsport 3s so the new pattern but they seem to have not rectified the issue a few have had with them. I now feel confident in the cars handling abilities whilst initially it was awful and I was scared to go into a corner anywhere near 50mph or driving at motorway speeds.