I would tend to disagree with the claim about uneven tire wear resulting from replacing a 60 series tire with a 55 series tire.
You state the only change you are making from the OEM tire is just the aspect ratio; e.g. 60 to 55 but everything else remains identical; e.g. section width (205) & diameter (15").
Therefore you are not significantly, if at all, increasing the tread width of your combination & no tread wear problems will result. It is fairly common to jump around between aspect ratios & section widths upon the same diameter wheel while still retaining an acceptable combination of the three. Just so long as you don't get carried away & attempt to run too wide or too narrow a tire on the OEM rim which will indeed cause problems as the sidewall will be distorted in both instances.
The difference in overall height of the wheel/tire combination between a 60 & 55 aspect ratio is pretty miniscule so you should be perfectly fine in regards to appearance as well as performance.
For more information, check out
www.tirerack.com & search their technical information pages.
