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Tire Talk: The problem’s the pressure

Published October 5, 2012

Q: I installed four new Hankook Optimo H727 tires, size P225/60R16, on my wife’s 2007 Outback. They’ve been rated for 160,000 km. I chose them because all the reviews I found including Consumer Reports, rated them high in every category. However, on a road with cross seams at a right angle to the direction of travel, they pound loudly. I took the car to the Subaru dealer, from whom I’d bought the car new, and was assured the suspension was fine (104,000 km). The dealer said the noise was the result of the hard rubber used to provide the service life.

I intend to replace these Hankooks with a smoother-riding all- season tire. I want to avoid another mistake. I’m considering: Bridgestone Turanza Serenity, Goodyear Assurance ComforTred, Michelin Primacy MXV4, Uniroyal Touring Tiger Paw and Yokohama Touring S.

Please give me your choice from the above five tires or your best suggestion.

A: Before buying new tires, make sure you are not running these tires at ridiculous pressures. They should not be run at higher pressures than indicated on the vehicle manufactures’ placard in the doorjamb or gas cap door. Too often, a misguided soul in the service department puts the pressures at what is indicated on the tire’s sidewall. This is the maximum load pressure, not the everyday going-down-the-road pressure.

In general the Hankook H727 is considered quite a smooth riding tire, so something seems off. I really think pressures may be the problem. Try dropping the pressures about 5 per cent and see what that does for the ride.

Having eliminated that pressure error possibility, consider different tires. However, be aware of the tire size you have, all the tires will be rated for high kilometres. A high-mileage tire will often be very stiff. It’s the tire casing that causes the thump, not the tread rubber.

The smoothest tire on your list is the Goodyear Assurance ComforTred. It has an extra layer of soft rubber between the tread and the carcass and that layer makes a big difference. I’ve tested this tire over expansion strips that were fully sticking up out of the pavement. The Goodyear ComforTred certainly soaked these up better than any other tire I’ve tried on this test.

thetireguy_1@hotmail.com

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