Tire Pressure (Street only)

[JustA5.0]

Tried doing a search, but only returned results about D/R and Slick pressure for the track.

A little background.

About a month ago I purchased two new summer radial rears for my 87GT. At the time, the tire shop was telling me how they recently got nitrogen, and asked if I wanted to try it in the tires, as they said it's not supposed to react to tempature change or leak out like air. I said "sure why not", figuring if it doesn't work as described, oh well it will be easy to deflate and replace with air again. Anyways, so the rears have nitrogen, and I'm including this incase it makes a difference somehow to PSI recommendations.

I check my tire pressure monthly for loss, and did that now. The rears had a whooping 40PSI in them. I deflated them to 30PSI, as that's what I've always run on all 4 tires. I've always practiced going with the sticker on the door jam for proper inflation of stock tire size. That sticker is long gone on my car, and I've realized the 30PSI I've been using was simply my decision. What was the stock recommendation for the 15" turbines in 1987? Also, since I don't have the stock tire size front or back for my car, I was wondering if the PSI should change any?
Fronts are 225/50/16 - Air
Rears are 245/50/16 - Nitrogen

Keep in mind that I'm looking for gas mileage and tire life, over contact surface footprint for launches and acceleration.

 

[cenok is family]

i've always put 34-35 in all four on all my cars...

 

[Mustang78]

35 all around on street tires, its not THAT important as long as you're within tolerance, nitrogen wont increase in pressure as the tire heats up and wont decrease when it's cold like air does..they're both weightless

~Mark~

 

[Mustang5L5]

The sticker listed 35psi as factory pressure with the 225 series rubber.

If you have wider tires, you can decrease pressure as the larger contact patch increases surface area and spreads out the weight of the car more. The newer Mustangs with 245 series rubber actual recommend 30psi as tire pressure.

There are ways to calculate idea tire pressure but you can generally stick to about 35 psi if on 225's and lower it a bit if you have 245's or 275's

 

[Aliate X]

I ran my DR's with 32psi and always got uneven wear, now I run about 18-20psi just in the rears (DR's) with good even wear

 

[Foxfan88]

i have 255/50s and i just run 35 psi, i run 35 psi it anything really.

but my 165 r 15 skinnies up front have like 45 psi in them

 

[JustA5.0]

Darn, took a little too much out then. Going to have to go back and get 4-5lbs put back in the rears. I must be thinking of newer cars listing around 25-30lbs for tire pressure, seems older models of whatever recommend 30+.

I ran my DR's with 32psi and always got uneven wear, now I run about 18-20psi just in the rears (DR's) with good even wear

Except I'm not running DRs as stated above

 

[wicked84gt350]

Hate to bust anyones bubble but the hole nitrigen thing is kind of a hoax because the air we breathe is 78% nitrogen and 21% oxygen the other 1 % is other gases so the other 22% other gasses than nitrigen is really not that big of a deal the only difference between nitrogen and oxygen is nitrogen molcules are larger the oxygen but only slightly not enough to effect the tire losing air. Welcome to the world of good marketing.

 

[Mustang5L5]

Hate to bust anyones bubble but the hole nitrigen thing is kind of a hoax because the air we breathe is 78% nitrogen and 21% oxygen the other 1 % is other gases .

It's that 21% oxygen that's the main difference. Nitrogen is non-corrosive to tires. Oxygen however is extremely corrosive and can compromise the rubber in tires as well as corrode the inside of the wheel.

Pure nitrogen is inert, so the rubber maintains it's integrity.

Nitrogen particles are also bigger than oxygen, so leaks are reduced. Usually it's the oxygen that leaks out of a tire since it's smaller.


Nitrogen-filled tires are used in aircraft and military vehicles.

It's not a hoax, it's physical properties are very real

http://www.sunliner.com/nitrogen/index.html

 

[JustA5.0]

Hate to bust anyones bubble but the hole nitrigen thing is kind of a hoax because the air we breathe is 78% nitrogen and 21% oxygen the other 1 % is other gases so the other 22% other gasses than nitrigen is really not that big of a deal the only difference between nitrogen and oxygen is nitrogen molcules are larger the oxygen but only slightly not enough to effect the tire losing air. Welcome to the world of good marketing.

Not bursting my bubble by any means. It was $10 extra and if it doesn't work, oh well it's 10 bones. If it works, I don't have to keep inflating my tires a pound or more each month.

 

[93gtmustang]

Call the tire manufactuer. Tell them your year and make of your car and tire sizes.
They will give you the recommended pressure that will work with your set-up, which will give your tires the best contact patch.
My 93 GT Mustang with the original size 225/55/16 tires was 30psi on the door tag.
Im running BFG G- Sports, 245/50/16 on the rears, and 225/50/16 on the fronts.
I called BFG and the said 30 psi on rears, 35 psi on fronts.