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Old 01-09-2012, 09:23 AM   #14 (permalink)
California98Civic
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Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,299

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.42 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
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Quote:
Originally Posted by euromodder View Post
There's no real need to go very high.
On normal passenger car tires, you'll already get most of the benefits around 45-50 psi .
45-50 psi is usually already beyond the specification of the car manufacturer, and into the tire manufacturer's sidewall max. allowable pressure range.

Increasing the pressure further , the effect on your MPG will become less and less noticeable - the law of diminishing returns.

By increasing the pressure further, you can also run into other problems, like a very harsh ride, wheel bounce, the suspension not coping with the bouncing wheels, uneven wear, ... so you need to watch the tires closely when going to or beyond the advertised sidewall maximum.
Something that is not part of this discussion yet: the ambient temp at which you pump/check tires and the day-to-day temp variation. I pumped my tires to 60psi in the warmest daytime temps available because I'm going to lose a lot of that pressure in the colder morning and evening hours. If you pump the tires in the middle afternoon to say 50psi, early the next morning you will not be running at that psi when you head off to work.

I'm at 60psi and the ride is harder, but the wear and handling are fine. We're not driving race cars ...

One thing to be aware of: if you have tire-pressure sensors on your car they might give you a warning if you go more than 5 or 6 psi over pressure.

Cheers,
james
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See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.



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