Why Do I Need To Measure My Brake Rotors Or Check The Style Of My Brake Pads?
Many Volvo models have multiple brake rotor diameter and 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.
With some models, if you look in Volvo's VIDA digital parts catalog, you will get references to the wheel size to determine which rotors a car has equipped. This seems simple enough but it is quite likely for a car not to have the factory installed wheels on it. A previous owner could have changed them or the dealership that originally sold the car could have swapped with different car to make the car more attractive.
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, to move the caliper out so it can reach around the larger brake rotor. This could involve replacement of a lot more parts than just the rotors: bigger brake discs usually means bigger calipers (or different caliper mounting brackets) and bigger brake pads.
Unfortunately for older cars, Volvo does not include the brake equipment information anywhere on the car, nor is this information stored in the VIN. If your car is a 1997 or earlier car, we suggest measuring the brake disc diameter as the safest way to make sure you're getting the right discs and pads.
For cars built after about 1998, you can use a Volvo VIDA service (subscription) to get a vehicle's build sheet details from the VIN. This information either has the original factory wheel size OR the brake system variant code that was installed at the factory.