Why do I need to measure my brake rotors or check the style of my brake pads?
We've never figured out why Volvo doesn't have an obvious way to determine which brakes are equipped on a car, but this has been an issue since the early 1970's.
Many Volvo models have multiple brake rotor diameter options and some models have multiple brake pad options. Most of the time, it is a choice of two sizes or styles, but in some cases, it can be as many as three or four. Usually, "Turbo" or Sport models have bigger brake rotor diameters than non-turbo or base models, but from our experience, this is not a reliable indicator.
On later models, if you look in Volvo's VIDA (Vehicle Information & Diagnostics for Aftersales) Parts Catalog, you will get references to the wheel size to determine which rotors a car has equipped. This is a very easy detail to check but it is quite likely that any given car does not have the factory installed wheels on it. A previous owner could have changed them or even the dealership that originally sold the car could have installed a different set to make the car more attractive. A previous owner may even have upgraded the brakes from a smaller diameter to a bigger diameter.
Why can't you just install the biggest rotors on your car? In some rare cases, this is possible, but usually the brake calipers or the brackets holding the calipers would also need to be changed. This could involve replacement of a lot more parts than just the rotors.
Some models use the same brake pads for all size brake rotors, but other models use different pads depending on the size of the rotor.
Other options and details of the car, such as paint color, interior color and even suspension details are included on the Volvo Product ID plate. Unfortunately, Volvo did not include the brake equipment information on this plate or anywhere else on the car. The information IS NOT encoded in the VIN number either.
Volvo dealerships do have access to more information than the aftermarket does. A volvo dealership can do a VIN inquiry on their Volvo Dealership network and get more information about a specific car. This information is not encoded in the VIN, it's simply in Volvo's database and was created at the factory. On later model cars, the brake equipment is included in this data.
Ultimately, it comes down to this: In order to be absolutely sure which brakes your car has on it, you will need to physically check.