depends what car you have but if that tire size works and your happy with it, why change it?

The first number is the width of the thread patch in mm.

The second number is the % ratio of the sidewall with the thread width (first number).

The last number is the size of the hole opening in inches (i.e your wheel size).

My advice.... check out www.edgeracing.com They have the best prices i have ever come across and shipping is quick because they are a big warehouse in south FL. Pay someone to mount and balance and your good to go.