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This WHOLE THREAD IS FLAWED because most of you are basing off your TIRES. Stop it already! The correct cold pressures for your vehicle's tires are listed ON your VEHICLE.
Here's some pressures, mid-30s psi, for recent year VW EOS:
A year or so ago I had someone tell me on this sub that car companies develop cars with specific tire make and model in mind, that once you don't run the exact same tire, the placard stating the correct pressures becomes obsolete and one should put the pressure on the tire sidewall into the tire
Just trust me - it's the difference in the shape between high-pro and low-pro. Remember, the low-pro is wider - you said it yourself more distance between centerline to each sidewall. I'm by no means a physics expert or mechanical engineer, but common sense tells you, when the container of air, the tire itself, is laterally spread out, it needs greater air pressure, 1-3psi probably, compared to a high profile, where that container is concentrated mostly right under the load it is supporting.
205/80 R17 is the same tread width as 205/40 R17. Same distance sidewall to tire centerline.
225/40 R17 is a different tread width than 205/40 R17. They're both considered low profile.
That simple error us why your opinion is untrustworthy. 205 defines the tire width in mm, 80 or 40 defines the ratio of tire width that is sidewall (80% or 40%) the RXX defines wheel diameter.
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Quote:
Originally Posted by Gungnir
205/80 R17 is the same tread width as 205/40 R17. Same distance sidewall to tire centerline.
225/40 R17 is a different tread width than 205/40 R17. They're both considered low profile.
That simple error us why your opinion is untrustworthy. 205 defines the tire width in mm, 80 or 40 defines the ratio of tire width that is sidewall (80% or 40%) the RXX defines wheel diameter.
It's in the shape of the X-section, G. Different pressures required for different shapes.
Location: Removing a snake out of the neighbor's washing machine
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Quote:
Originally Posted by HumbleMerchant
A year or so ago I had someone tell me on this sub that car companies develop cars with specific tire make and model in mind, that once you don't run the exact same tire, the placard stating the correct pressures becomes obsolete and one should put the pressure on the tire sidewall into the tire
Well what they told you was wrong - at least that last apart about resorting to the tire sidewall stamping.
The same thing applies to non-OEM tires or sizes: Start with the B-pillar placard recommendations, then up them or down them from there as necessary.
My wife's older Toyota and my recent Hyundai both specify the same tire size, but recommend different cold pressures on their door placards. Why? Think about that for a while. Should be obvious.
Huh ??? "The max load pressures or not for Max load," ?????
Why don't you post a picture of the placard on your car..
Again the pressures listed on the sidewall of the tire is the maximum pressure is that the tire can withstand.
The pressure is listed on the placard affixed to the car on what the manufacturer recommends for various conditions and loads ... it's pretty obvious. Also the owner's manual, or somewhere else of the car, has a listing for the max capacity of the car ... just like a boat, people and gear.
Max sidewall is not the maximum pressure the tire can take, but rather it's the tire pressure needed to carry the tire's rated maximum load. Any pressure higher (or lower?) than this begins to reduce the tire's safe load capability.
Tire pressure is definitely not simple, and door placard numbers are indeed just recommendations. They're often very good recommendations, but they do in fact only apply exactly to the original tires. Higher pressure reduces tire running temperature, often increases maximum safe speed, and usually slightly increases tread longevity. It changes how the tires wear (not necessarily more in the middle). It increases ride harshness. It lowers rolling resistance which improves fuel economy. Higher pressure typically reduces dry grip but increases hydroplaning resistance. It changes tire noise (usually for the worse), affects load capacity, and can have a large impact on handling, either for better or worse depending on the vehicle.
Door placard pressure is a safe bet, put there by an engineer to get a certain combination of factors, sacrificing some to improve others. But, it's definitely something you can deviate from a little, safely, if you want a softer ride or better economy, or notice your tires aren't wearing evenly edge to middle.
I’m glad i grew up in a time when we just put air in our tires according to the manufacturer. Today younger drivers make filling your tires with air a scientific study. Stop making simple things lik air pressure so complicated.
I’m glad i grew up in a time when we just put air in our tires according to the manufacturer. Today younger drivers make filling your tires with air a scientific study. Stop making simple things lik air pressure so complicated.
This was always there, we were just ignorant of it.
I run a bit higher pressure in my tires because they wear better, because I don't mind the extra bit of harshness, and because I appreciate the improved gas mileage.
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Quote:
Originally Posted by EckyX
This was always there, we were just ignorant of it.
I run a bit higher pressure in my tires because they wear better, because I don't mind the extra bit of harshness, and because I appreciate the improved gas mileage.
I run at or just above vehicle door placard numbers, because I like heavier steering feel. 4psi or more over door placard and most recent cars to me steer like they have Tourrettes - too twitchy! I like having to use actual muscle to make turns, and like the car to stay centered in my lane on highways.
I’m glad i grew up in a time when we just put air in our tires according to the manufacturer. Today younger drivers make filling your tires with air a scientific study. Stop making simple things lik air pressure so complicated.
You were way ahead of me. In my day we just looked at the tires. If I wanted to be really accurate, I would push my thumb in and see how much more air it needs. We lived.
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