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Discussion Starter · #1 ·
Hey all,

Ok here is my situation. I have 17×6.5" rims on a 2013 mazda 3 sky. I think they might be originally Mazda 5 rims based on the pattern.

I bought the car used 5 years ago and they had brand new goodyear eagle sport all seasons 215 45 17 on them. Thought the car felt great. handled great. Ran them at about 33psi.



I unfortunately had a blowout last week

so i needed to replace my tires. Decided to try Michelin pilot sport as 4..same size 215 45 17 and set them to 34psi



Problem is these things feel like mush. Like terrible. Almost nervous inducing...

I know the original tires were 205 55 16 and the door says to set those to 36.



Wouldn't 215 45 17 tires run at a bit lower pressure?? Like i said, the eagles were always set at 33 or 34 and they felt great.



Is there something I'm missing? Should the new Michelin be set much higher?? I'm kind of at a loss



Thanks so much for your help.

Cheers

Dave
 

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Your vehicles tire pressure should be set to the recommend PSI that is in your door jam information. Going differently will effect many aspects of your vehicles designed abilities. It is as simple as that.
Forums debate and constantly input user chosen psi which they feel is better for them. But I have yet to see a member on any forum that was a chassis or drivetrain engineer for any auto manufacture?
 

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Discussion Starter · #3 ·
That's totally fair. I guess what I'm confused about is how the same size tire (both 215 45 17) set at the same psi can differ night and daywhen both are new and both in the same tire category. The goodyears felt very firm and responsive. The Michelins honestly feel like driving on balloons and its honestly scary at the exact same pressure the goodyears were. Same rims.

The original tires/wheels on the car were 205 55 16 and supposed to be set at 36.These rims are 215 45 17 and one set of tires felt perfect at 33psi and replacements feel like marshmallows.

Does anyone run this size tire at a higher psi? I don't see how i can drive with these of i don't

I'm just curious
Thanks
 

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rough rule of thumb (i am braced for the fallout)
set to rim diameter x2 plus 2
so 17x2 +2 =36psi
different tyres have different sidewall construction and different tread patterns
the eagles are a hard tyre where as the michelin are a soft tyre
 

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Discussion Starter · #5 ·
rough rule of thumb (i am braced for the fallout)
set to rim diameter x2 plus 2
so 17x2 +2 =36psi
different tyres have different sidewall construction and different tread patterns
the eagles are a hard tyre where as the michelin are a soft tyre
Thanks for the answer!
I'm just a little leery of having to pump up the tires this much as the wear might be more I the middle and the contact patch isn't as much as it should. I guess I'll just watch the wear pattern. But i don't think i can drop then less than 38. It's too vague

I should have just bought the goodyears again haha. They are both high performance all seasons..i just find it hard to beleive the Michelins have that much softer sidewalls based on all the reviews.

But pumping these things up to 38 isn't the craziest thing you guys have ever heard of doing?
 

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The suspension brakes and other chassis engineering really works around following the recommend tire pressure. Whe people decide to alter from how a car was engineered they are guessing on armchair theories.
The only real time you do not follow the recommend tire pressure is for competition use on a specific TRACK in which you are not driving a tire used and designed for a daily driver.

The simple question I always ask when I read responses members on various forum posting their input about tire pressure is to show me from any tire manufacture or auto manufacture that agree with their tire psi choice and post that information so we all can see it is sound advice. Even when you contact tire manufacture the most frequently answered question about tire press is to follow the auto manufacture recommendations.

Those braking specification at 60-0 mph are on a vehicle with exactly the recommend tire pressures. So hey maybe you know a formula that will show a different result using lower or higher tire pressure then recommend on a 200 foot skid pad or braking distance?

Get my point.... forums are a great place to share information but read between helpful and not the best information.
 

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rough rule of thumb (i am braced for the fallout)
set to rim diameter x2 plus 2
so 17x2 +2 =36psi
different tyres have different sidewall construction and different tread patterns
the eagles are a hard tyre where as the michelin are a soft tyre
So you are great example of information that is not the best. No accounting for ambient temperatures or road temperatures. Not asking what the estimate weight of the vehicle. I could go on. So who's rule of thumb and what tire manufacture or auto manufacture ever posted Data to support that?
 

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lout really you went on the internet to find a video that support your thoughts. :ROFLMAO: Yup the world we live in.:rolleyes: Disregard those that know and have real world data and testing like the auto manufactures and tire manufactures and go with a DIY video. :ROFLMAO:
I am sorry please do some personal testing on what your posted earlier using at least an accelerometer and data log the information and return to this thread and post it up. Please include all the operating perimeters i.e. deltas.
Otherwise really posting 1 or a dozen of those ridicules video disregards the safety and integrity of a vehicle.
 
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