Bearing down and pressuring up

"Hi Brian, Like so many that write to you, I too enjoy your column and advice on a wide range of topics.

I have a 2010 Ford Taurus with 85,000 km. The kilometers are light duty and mostly highway. Rarely would there be more than 2 passengers or a few suitcases. As of this week I have replaced 3 of 4 wheel bearings. Front two bearings were done six months ago. Right rear bearing this week. These are not inexpensive repairs.

The OEM tires and rims on the car are 18 inch, my question is do today's larger tires add significant stress on bearings and are the Taurus's bearing assemblies up for the job? Are there other factors that might contribute to bearing failure?" Phil In my experience, unlike many parts on autos, wheel bearings don't tend to fail strictly because of mileage. The experience on this Taurus isn't usual according to my local dealer service and parts department contacts. The question on wheel size affecting these failures is a good one. While 18" tires and rims are large, the wheels are usually constructed of a lighter weight alloy which offsets the size. So as weight isn't a factor, the improved grip of larger rubber might be. Let me explain. Drivers quickly adapt their driving styles to the limits of the vehicle they are operating. No one wants to be unsafe or a discourteous driver, but lighter vehicles with powerful engines build on very responsive suspension and steering systems, tends to bring unforeseen consequences. Sometimes the tire grip is just too much for the car given a particular set of road and weather conditions.

Most wheel/hub bearing assemblies fail from excess forces being applied to them. Lateral impacts on curbs, direct collisions with potholes, constant poundings from unpaved roads, and even aggressive cornering can lead to their demise. Alloy wheels can exacerbate these problems as they tend to seize on the hubs over the course of a few months of Canadian winters. Then when it comes time for the seasonal tire changeover, techs must often resort to hammering the rims off. A heavy hammer is also often employed when trying to remove brake rotors during routine maintenance. All this pounding can have a negative effect on wheel bearings.

My advice is to always stick with a well-known brand name part with the longest warranty possible when replacing a hub/bearing. Ford recently changed the warranty on their replacement parts and most are now covered for two years with no distance limitation. There are plenty of cheap offshore after-market brands, but they seldom deliver a life-span most consumers expect for the price. When having the tires removed for rotation or seasonal change, ask the tech to paint a coating of heat-proof lubricant on the hub where the wheel contacts it. This might also make a big difference if you have to change a flat on the side of the road. Of course, avoiding curb kisses and potholes and wash-outs is up to the driver.

The Rubber Association of Canada recently revealed some surprising stats from a Leger poll of over 1,000 Canadian drivers completed in early April. With the automobile travel season at our doorstep it's astounding that: -69 per cent of drivers don't check their tire inflation monthly, -31 per cent think they only need to check their tire pressure when it appears tire pressure is low, -45 per cent of motorists do not know where to find the correct inflation pressure for their vehicle, -65 per cent do not know that tire pressures should only be measured when tires are cold.

Other than the increased fuel consumption and shortened tire life to consider, the risk to road safety grows with each pound of air pressure lost. Underinflated tires can be a blow-out hazard waiting to happen, especially when rolling on a heavily loaded vehicle in warmer ambient temperatures.

"These findings should be a wake-up call to Canadian motorists," says Glenn Maidment, president of The Rubber Association of Canada, which represents tire makers. "Drivers can guarantee optimal tire performance, lower their fuel bills and protect the environment simply by learning a few tire inflation facts and measuring air pressures monthly to ensure their tires are inflated to the vehicle manufacturer's recommended level."