I just picked up an '06 V70 and it has 17" rims with summer tires. I found a winter wheel package that has Stratus 16x7 rims. Will these fir an '06?

Check Volvo's site in the accessories section - they now list many wheels, models, and years of cars.

You might find a listing of those wheels for your car.

You need to find out the brake rotor diameter. Either 11, 12, or 12.5 inches. 11 inch rotors will allow for a 16 inch wheel to clear the caliper. The 12 inch rotor (305mm) might be too close for comfort with a 16 inch wheel.

Take a good look at your rotor/wheel clearance, is it more than 1/2 inch? Be prepared to remove a wheel and test fit the 16 inch wheel before you buy.

BTW, does your car have TPMS?
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Keeping it running is better than buying new

I don't have the TPMS on my '06. The rims are aftermarket and fit fine. I did have to remove the 10mm bolt that holds rotor in place.

One piece of data: I use 15" alloy Volvo wheels for snow tires on my 2007 V70 and have had no issues. My car came with 16" wheels. I did mount the wheels on the car before installing the tires to make sure they cleared the calipers. I have TPMS, but I did not install sensors in the snow wheels - so the TPMS warning is on in the winter. In New York, it still passes state inspection if the TPMS is not functioning properly.
Steve