The roadwheels are made of pressed steel and it is important to take them off periodically to clean dirt and mud off them inside and outside, as well as inspect them for signs of rust or rim damage and rectify any issues as necessary. A smear of light grease must be applied to the studs of the wheels and then the nuts screwed on, which should be tightened to the specified torque. The tyres are of radial construction and it is not advisable to mix constructions, regular check and maintenance of tyre pressures. If the wheels have been balanced on the car they should not be moved around the vehicle to equalise the wear of the tread, but instead the relationship of the wheel studs to the holes in the wheel should be marked for exact replacement to maintain balance. Conversely if the wheels have been balanced off the car, they may be turned so as to equalise the wear, including the spare wheel in the pattern, but with radial tyres, only front and rear wheels on the same side should be interchanged. Balancing the wheels is important for good steering and roadholding and rebalancing is important when the tyres have been in use for around half their useful life to make up for the loss of tread rubber due to wear. Regular checking of tyre walls and tyre treads for cuts and damage is required and any obvious problems should be repaired by professionals.