2010 Volvo S40 Owner's Manual - Page 191

07 Wheels and tires Wheel nuts Wheel nuts WARNING Never use the short type of nut for aluminium wheels. This could cause the wheel to come loose. Aluminum wheels - high nut Only the high type of nut can be used for aluminum wheels. This is considerably different from other types of nut because it has a rotating conical thrust washer. NOTE G020324 This nut can also be used on steel wheels. Low nut. High nut. There are two different types of wheel nut, depending on whether the wheels are steel or aluminum. Lockable wheel nut If steel wheels with lockable wheel nuts are used in combination with wheel covers, the lockable wheel nut must be fitted to the stud nearest the air valve. The wheel cover cannot otherwise be installed on the wheel. Steel rims - low nut Steel rims are normally secured using the low type of nut, although steel rims may also use the high type. 07 191