Now pry out the plastic covers on the end of the rubber tubes and you will find 2 bolts/slides holding the caliper to the bracket remove both of your 7mm allen(socket) caliper slide bolts. Just like the front brakes. With the slides now removed lift the caliper off the rotor. If you have a rust ridge on the rotor (you should check the rotor with a micrometer for proper spec and make sure it's not undersize. Min. spec is 8.5mm) I use a flatblade screwdriver and slide it between the outer pad and the rotor pulling outward on the screwdriver inturn compressing the caliper piston a bit as shown below.

This is typical of what you might expect if you opt to run 205/55/16's on your 850 Volvo. These pictures were taken after only a few thousand miles. The car is fitted with the Volvos Sport R suspension. No other suspension modifications were present on the car. Below are a few other pictures.

The tire shown above is a 205/45/ZR17 88w. 205 is the width of the tire in millimeters. The next number is the aspect ratio. In this case 45 represents that the side of the tire is equal 45 % of the width. 205mm x .45 = 92.25mm, or about 3.63 inches. A popular misconception is that sports cars have lower profile tires than what is used by Volvo. In many cases this is not true. Take a Corvette for example. The common tire size is 275/40/ZR17. The aspect ratio is lower but the tire is also much wider. 275mm x .40 = 110mm or about 4.33 inches. This is a full 7/10's more sidewall. The next number on a tire sidewall is proceeded by two letters. The first of the letters will be the speed rating, explained later. The second, usually R, represents that the tire is radial. The following number is the rims diameter. The final number is the load rating. In this case 88w.