Wider tires will do two things to your ride... well, three actually, but one is VERY minor.

1. Wider tires will give you better traction in dry weather, but... unless they are properly channeled, you are more likely to hydroplane in wet weather.

2. There is more unsprung weight, this will lower your acceleration rate slightly as unsprung weight is the biggest enemy of acceleration. (minor if you are not much wider than stock).


3. Wider tires will make your car tend to be guided by every bump and crack in the road. The wider the front tires, the more severe the tracking. You can compensate for this by simply paying attention.

Hope that helps.