Plus sizing means increasing the size of your car rims while decreasing the overall area of the tire. Understand the advantages and disadvantages before having work done on your car. Plus sizing makes the tire wider and reduces the flexibility of the tire, allowing for better handling and braking on dry surfaces. Many people like the way plus sizing looks, but this is an expensive process, requiring a new set of rims and tires. The ride may not be as comfortable, as there will be less air between the tread of the tire and the wheel.