Unscrew the center cap of the Polaris 280 wheel using a flathead screwdriver. Gently tap the plastic washer under the cap with a screwdriver to loosen it, then remove it by hand.
Pull on the Polaris 280 wheel. If the wheel easily slides off the wheel rod, remove the ball bearing inserts on both sides of the wheel. If the wheel does not slide off the wheel rod, gently tap the front side ball bearing insert with a screwdriver to loosen it, then remove the wheel. Polaris ball bearing inserts are expensive components to replace, any in good condition should be saved and used in the replacement wheel.
Insert the previously removed ball bearings or new ball bearings into the new wheel. Ensure the bearings fit securely in the wheel. Carefully slide the replacement wheel onto the wheel rod with the groves on the rod lining up with the groves in the center of the wheel. Set the plastic washer into place on the visible ball bearing. Insert the center cap into the center of the wheel and screw it back into place with a screwdriver.