2008 Volvo S40 Owner's Manual - Page 166

Steel rims - low nut Steel rims are normally secured using the low type of nut, although steel rims may also use the high type. WARNING Never use the short type of nut for aluminum 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 This nut can also be used on steel wheels. 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. 183 07 Wheels and tires Tire rotation Summer and winter tires When switching between summer and winter tires, mark the tires to indicate where they were mounted on the car, e.g. LF = left front, RR = right rear Tires with tread designed to roll in only one direction are marked with an arrow on the sidewall. Incorrectly mounted tires impair the car's braking properties and ability to force aside rain, snow and slush. The tires with the most tread should always be at the rear (to reduce the risk of skidding). Contact a Volvo workshop if you are unsure about the tread depth. Tire rotation Your vehicle has no recommended tire rotation. The following information is intended to help you understand why. Tread set As a tire ages and the rubber cures, front and rear tires set at different angles. Therefore, if tires are rotated, the tread will eventually set at an angle that is a compromise. Even if ride, handling, and road noise may still seem acceptable,