Mounting summer tires or changing to winter tires happens every year as temperatures rise and fall. If a vibration is noticed shortly after having a tire mounted, it may be caused by the tires slipping on the wheels during acceleration or braking, placing the imbalance point of the tire away from the weight location.
Caption: Wheel slip mark
Wheel slip is most common on clear-coated or chrome wheels with very smooth bead seat areas, but it may also occur on other alloy or steel wheels. Most slippage occurs immediately after mounting.
Wheel slip normally occurs when an excessive amount of lubricant is used, lubricant is applied in the wrong locations, or the wrong lubricant is used. Improper lubricants, non- preferred lubricants or improperly diluted lubricants may contain excessive moisture or components that do not dry sufficiently, resulting in an interface between the tire and rim that is excessively slippery.
Checking for Wheel Slip
Vehicles that return immediately (the vehicle has been serviced within the last couple of hours) with ride disturbances and out of balance assemblies should be checked for wheel slip. Wheel slip can be checked by placing a temporary mark on the tire at the valve stem. After driving the vehicle, if the wheel slip is less than one inch, then wheel slip is probably not contributing to a ride disturbance. When wheel slip is greater than one inch and a ride disturbance is felt on the test drive, wheel slip may be causing the vibration.
To eliminate wheel slip, the tire beads should normally only be lubricated from “heel to toe.” Lubricant applied outside the heel-to-toe zone will cause the tire to have reduced grip on the wheel and increase the likelihood of slippage. When lubricating the wheel, lubricate the safety humps, leave the rim flanges dry and lubricate the drop center area only for difficult-to-mount tires.
To minimize rim slip, always use commercially available lubricants made for bead seating to assist in tire mounting. Paste-type lubes are recommended because the application can be better controlled and paste type lubes will not drip onto areas that should not be lubricated. If lubricants that require dilution are used, carefully follow the lubricant manufacturer’s instructions. Under-diluted mixtures will not dry soon enough, which may cause wheel slip. Over-diluted mixtures will dry too fast and may hamper proper bead seating.
Lubricants also must be properly stored. The container must be kept covered to prevent the evaporation of drying agents. Always check the lubricant’s expiration date. Once the expiration date is reached, dispose of the remaining lubricant.
After tire mounting, the vehicle should not be driven aggressively (hard acceleration or braking) for up to 24 hours to allow the lubricant to dry and for the tires to achieve maximum adherence to the wheels.
For more information contact the ACDelco Technical Assistance Centre at 1-800-263-3526 prompt 2.