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post #31 of 33 (permalink) Old 08-05-2015, 07:45 AM
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Default 90K with Michelin Energy Saver A/S

I found no problem inflating tires to 40 rear, 42 front and just bought new Michelin Energy Saver A/S after getting 90,000+ miles out of previous identical tires.

Local tire dealer grudgingly gave me those pressures, saying, "You'll wear them out quicker." So I guess I could have gotten over 100,000 miles.

No unusual wear pattern; car tracked straight as an arrow on x-way; no problem with handling.

I once got 60+ mpg (display said 63, always too high) from Kansas City to Cincinnati (close to 600 miles) on a summer weekday, going 55mph except when traffic dictated going faster. Filled up in KC and drove straight through except for usual stops.
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post #32 of 33 (permalink) Old 08-14-2015, 12:58 PM
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If you are using helium instead of regular air, there is no problem with slightly over-inflated tires. But if you are using regular air, then don't over-inflate in hot weather.

Safety guidelines do not recommend over-inflating in hot weather no matter what you use to inflate your tires with, but I have never had a problem in hot weather while using helium in my tires. I live in Arizona.

The additional increase in mileage with over-inflated tires may not be significant depending on your driving habits.

Jack-rabbit starts and excessive high speeds reduce your mileage considerably.

John C.

Originally Posted by JCPrius2008 View Post
Hi All,

Got a questions for you guys out there...

I own a Year08 Prius. I do try to make sure the tires are inflated according to the values recommended by Toyota. This means that I'm going by the values indicated on the sticker found on the door (is it the driver side or front passenger side? I can't remember which).

Having read other posts earlier, it seems to me that many are claiming 42front/40back would boost MPG even more! So questions are:

1) Is it save to inflate higher than the manufacturer's recommended values? I'm also worried the tire would burst on me all of a sudden...
2) Why 42/40? Did somebody out there do some kind of comprehensive tire pressure test and conclude that 42/40 is the sweet spot?

Thanks all for your help! Look forward to hear from you guys!

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post #33 of 33 (permalink) Old 09-04-2018, 05:11 PM
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I inflate the tires slightly more than what is stated in the manual. Tires always loose pressure over time. I don't think a reasonable increase in pressure is harmful, since the stiffer the tire, the less it will flex, the less it will heat up, and the less it will gain pressure. But what do I know, I've only been checking tired inflation for 55 years.
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