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Originally Posted by michael.long8
original thread:
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8) Check tire inflation regularly
Make sure that your tire pressures are, at minimum, set to manufacturer specifications. The higher the pressure, the less rolling resistance.
Remember that pressure is affected by ambient temperature. As temperature drops, so does your tire pressure, so keep track as the seasons change.
my post:
I am aware that properly inflated tires do increase mileage over tires that are underinflated; however, as indicated above, higher pressure equates to lower rolling resistance, which leads to my question. Has anyone done a real-life study to see how much sooner their tires wear out because of overinflation? |
Tire pressure is a balancing act. Overinflation does give you a lower rolling resistance as you've pointed out. However, overinflation also gives you a reduced contact patch. This means at speed you will not have as good a handling or braking - especially noticeable in poor conditions, rain, snow etc.
The above image should make it evident why your tires will wear faster. There are also a few other things to think about. As you drive (high speed especially) the tire friction turns into heat. Heat dissipation is one of the specifications that give you the tire speed rating. With this heat you have expansion. Now if you over-inflate then get them hot, it will at some point become a safety issue.
My old man worked at Michelin for 25+ years. I can give you a few snippets of insight from talking to him. First, the grade a manufacturers test the @#$@# out of their tires. So the maximum PSI they give accounts for a fully loaded vehicle at maximum speed and they multiply it by a design factor (Fudge factor if you will).
As a family we always got the employee tires (blems). When they were used up we had to return them and they'd cut them up and do all sorts of tests (like blow them up!) to make sure they fared well with the safety factor. Ongoing R&D and this gives you insight into why a Michelin costs more than a wang tire.
Tire manufacturers put a lot of R&D into rolling resistance. This actually sells tires. Carmakers have their vehicles tested with the OE supplied tires for fuel economy and EPA listings. Producing tires with lower rolling resistance helps these figures so carmakers will bias the tire choice for the best results.
With overinflation you get gains because there is less tire deflection as it rolls. If you have a lighter car that helps too, so take your junk out. Runflat tires tend to have slightly better rolling resistance because they have stiffer sidewalls - less deflection.
Here is an interesting tidbit too. Overinflation helps your city fuel economy more. At higher speeds tires have a better rolling resistance. Centripedal force pushes the tread out and there is far less deflection at speed.
I would never advise overinflating a 32psi tire to 80. That's more than double the intended operating pressure! One person doing this saying well my tires didn't blow up does not compare with tens of millions of driving km tested by teams of engineers. While you can get away with some overpressure that's downright unsafe. Have a look at the lawsuit against firestone for the exploding tires. Overinflate them and go 150kph for an extended period of time and they blew up.