Tire MAX PSI

[-Jayson-]

okay i got my toyo proxies and rims put on the car. The tires are 215/45/17. The MAX PSI on the tire say 50 PSI, well at 50 PSI the tires were way to hard and made driving it more annoying than anything. So i lowered the PSI to 45 PSI all the way around. The ride is softer now, but im curious as to how low of PSI is safe to go on them? ALso would it be safe to put the rear down to say 35-40PSI just because there is barely any weight on the rear end. I can understand leaving the front a little higher because those take the most road abuse. Also how low below max PSI do you guys drive aroundon your tires? And what is the tire size.

[TerminalVelocity]

how much are you stock tires inflated psi-wise?

Put it at that, maby a lil higher.

[TheStang00]

Originally Posted by TerminalVelocity

how much are you stock tires inflated psi-wise?

Put it at that, maby a lil higher.

well dont lower profile tires need more psi... because they have less volume so they need more psi to exert the same force.

[TerminalVelocity]

they arnt that low profile! the ammount of air is different, but the pressure is the same.

15psi is still 15 pounds per square inch weather its in a large tire or lil tire.

But it also depends on the weight of the vehicle. Easy way to tell is put it a lil above stock weight and look at the tire, it should have most of its tread on the ground, not be a lil flat, and not be too rounded (overinflated)

[CBFryman]

Originally Posted by TheStang00

well dont lower profile tires need more psi... because they have less volume so they need more psi to exert the same force.

Someone failed physics and doesnt know much about Hydralics.

Max PSI on my truck tires is 45PSI...i run them at 25. They are 265/75's i think that is alot of surface area for a 3200lb vehcile. Air them down untill you get a little buldge in the tire then air htem up untill it is gone, propper pressure is about even tire ware, not load, at leas on light non tow vehicles.

[rice(er)]

isn't the psi on the sidewall the MAX for the tires? i wouldn't go max on them, i think you'll be fine with 40-45 psi, remember to measure them cold

[CBFryman]

yeah cold on a warm day...cold on a cold day = flat tires on a hot day.

[TheStang00]

Originally Posted by CBFryman

Someone failed physics and doesnt know much about Hydralics.

Max PSI on my truck tires is 45PSI...i run them at 25. They are 265/75's i think that is alot of surface area for a 3200lb vehcile. Air them down untill you get a little buldge in the tire then air htem up untill it is gone, propper pressure is about even tire ware, not load, at leas on light non tow vehicles.

you know you really look stupid saying that.

i wish i could remember the exact equation but its been a while. but with a larger volume a lower psi will exert just as much force. a normal car tire needs about 35psi. do you know what would happen if you were to put 35 psi in a big tractor tire? well it would explode and probably kill you thats all. a big tractor tire only needs about 13-14psi to be just as firm as a car tire.

someone needs to stop thinking they are a physics god cause they are in high school physics.

Originally Posted by TerminalVelocity

15psi is still 15 pounds per square inch weather its in a large tire or lil tire.

as explained above, that is a huge difference in a much larger/smaller tire

edit- actually i believe its a very simple problem... 35 pounds per square inch, with a small tire, you have fewer square inches. which means less force is being exerted on the tire. calling for more psi. imagine the size of a combine tire, 35psi on a tire with that much area would be such a tremendous amount of force... think about it, its quite simple.

[clawhammer]

When you at the strip, wouldn't you inflate the wheels that aren't the drive wheels to max psi, and the drive wheels to minimum, or even below that for best traction? Wouldn't you want to run that way on the street?

BTW, let's see some pics Jayson.

[-Josh-]

32-34 psi is recommended on street/passenger tires. Anything over 40 is generally only used on truck tires, it can cause uneven tire wear on passenger tires, same thing with under inflating.

[CBFryman]

Originally Posted by TheStang00

you know you really look stupid saying that.

i wish i could remember the exact equation but its been a while. but with a larger volume a lower psi will exert just as much force. a normal car tire needs about 35psi. do you know what would happen if you were to put 35 psi in a big tractor tire? well it would explode and probably kill you thats all. a big tractor tire only needs about 13-14psi to be just as firm as a car tire.

someone needs to stop thinking they are a physics god cause they are in high school physics.
.

Thanks for agreeing with exactly what i said. A lot of area needs less pressure than a smaller area.

Could that formula be F/A = F/A?

Stop being a jackass and learn when someone is being jokingly mean.

[TheStang00]

Originally Posted by clawhammer

When you at the strip, wouldn't you inflate the wheels that aren't the drive wheels to max psi, and the drive wheels to minimum, or even below that for best traction? Wouldn't you want to run that way on the street?

BTW, let's see some pics Jayson.

well generally you would be right, but im pretty sure that with radial tires the best traction comes at the recommended psi to be at for normal use.

Originally Posted by cbfryman

Thanks for agreeing with exactly what i said.

if thats what you were saying... what was the point of this response

Originally Posted by cbfryman

Someone failed physics and doesnt know much about Hydralics.

and incase you didnt know, you really cant tell voice tone in typing... looked more like you were mocking me

[alphalanos]

I usually inflate mine to about 10 psi below max. Like my Hankooks are 44psi max I usually keep them at 35psi. They are wearing well with the exception of a bit too much negative camber. Personally I like to have a better feel of the road that is associated with slightly firmer tires.

[-Josh-]

The problem is when you over inflate them it creates a lot of friction because of the road force variation. To get optimal performance out of your tires they should be at a reasonably low pressure (30-35) and the wheel should be balanced properly.

[turtlecrxsi]

I run my 185/60-14s at 36psi. They are fine anywhere from 38 to 32 psi. Anything lower than 32 and the tires are squashy. Anything over 38 and they are too firm with seemingly less control. Use the same principles as stated above... you want a nice contact patch. Don't over-inflate or your ride will be harsh and your steering will feel loose. Don't under-inflate or your ride will be squashy and your steering will be harder...