Originally Posted by as_merrill
true to a sense, if he is getting the stock size, the performance goes in the toilet. My tires handle great through the canyons for a 195/60/15, better than my stock michelins mxv4's. My tires also handle great in the rain, hardly any hydroplane if at all. If he is looking for performance, he needs to get at least a 205/50 because that will cut down on sidewall movement and a wider stance, but he will sacrifice the huge wheel gap if his car is not lowered.
You should always maintain the same overall wheel diameter. simply getting a wider and lower profile tire may improve grip, but it throws off the suspension geometry which can put stress of certian components. It also creates speedo error. IF you really want a lower profile, you should increase rim diameter (buy new wheels). In many caeses this also improves handling by reducing unsprung weight.. since it usually results in a net loss in wheel weight. (more lightweight metal, less heavy rubber)