Let's talk tire pressure

[69GTX]

I run them from 32-38 psi depending on which season. I'll let them run down to 32 and then pump back up to 36 or so.

My butt is not calibrated so I can't say I've ever noticed any handling or mpg difference in the 30-38 psi range. I'd rather let tire pressure slowly vary in this range so wear on the tire varies from varying foot prints.

In winter, the denser air can add 10-15% additional resistance against your car leading to lower mpg. That's a bigger effect than 5 psi tire pressure.

 

[TheStig83]

Originally Posted By: Linctex
My 265/70R-17's say max 44 psi on the sidewall, that's where I run them. I don't care what the door tag says.

What kinda vehicle are these on and what does the door placard say for psi? 44 psi is insane. You do realize tires create heat and causes the tire pressure to rise while driving right? So if your at 44 psi then when going down the freeway your probably at 46 to 47 psi. That's way over inflated. Plus all your rolling on is the center of the tire causing it to wear out prematurely and just think of all the other stress and damage it's doing to the vehicles ball joints, struts, shocks, control arms, tie rods. Not only that but it's gotta ride horrible at that tire pressure. Does it kill your back when you hit bumps? Do you replace your tires every 10,000 miles at that psi? Not trying to be mean so please don't take offense to it. I'm just trying to rap my head around your logic of running max sidewall pressure in your tires.

 

[SirTanon]

Originally Posted By: Linctex
My 265/70R-17's say max 44 psi on the sidewall, that's where I run them. I don't care what the door tag says.


Welcome to blowout pressure when it gets hotter.

 

[TheStig83]

Originally Posted By: SirTanon
Originally Posted By: Linctex
My 265/70R-17's say max 44 psi on the sidewall, that's where I run them. I don't care what the door tag says.


Welcome to blowout pressure when it gets hotter.


Exactly. That's just asking for trouble

 

[oil_film_movies]

I always inflate to 4 psi over the door placard. Tire loses pressure over time, so I check weekly, and get to an air pump when the tire pressure gets 1 psi under the door placard numbers. Practical good system.

I rented a car recently, and I noticed Hertz often inflates tires that are supposed to be at 33 psi cold to 41 psi (still under the 44 psi sidewall limit anyway). I noticed the tires rode hard, and deflated them to 36 psi for my rental period, a mere 3 psi over the door placard value.

 

[Farmer]

I run the pressure stated on the door on most except one vehicle. 50 PSI F/R instead of the specced 65. 60 if I'm towing.

 

[Starman2112]

For optimal wear, take the max inflation pressure on the sidewall and subtract 10%. For example, 40 psi max, run at 36 psi. If the ride is too harsh, bleed 2 psi and drive again. Repeat until you're happy with the ride but don't go below the recommended psi on the door sticker.

 

[SaturnIonVue]

For the past several decades I've run my tires about 3-psi over the sticker. Never had issues with uneven wear or shorter tire life. My current car is recommended at 30-psi, which as most manufacturers seem to favor ride quality over tire life. I run all tires at 33-psi year round unless I'm going on a trip of hundreds of miles on the interstate, then I set all tires at 35-psi. I certainly believe that if you use the sticker PSI you most likely will cut into the tires lifespan, but will have a smoother ride while doing so. In concert with psi settings I believe tire rotation between 5K to 8K is vital for most cars to maximize tire life. You can walk around in most any parking lot and tell who rotates their tires and who doesn't by looking at the wear difference between the back/front tires.

 

[Linctex]

Originally Posted By: TheStig83

What kinda vehicle are these on and what does the door placard say for psi?


Full-Size Ford, 5940 lbs

Originally Posted By: TheStig83
44 psi is insane. You do realize tires create heat and causes the tire pressure to rise while driving right? So if your at 44 psi then when going down the freeway your probably at 46 to 47 psi. That's way over inflated.


Do you honestly think it's going to go up 2-3 psi? I've checked them , HOT in July Texas and they don't go up maybe 1/2 a psi at the most (from ambient).

Originally Posted By: TheStig83
Plus all your rolling on is the center of the tire causing it to wear out prematurely and just think of all the other stress and damage it's doing to the vehicles ball joints, struts, shocks, control arms, tie rods. Not only that but it's gotta ride horrible at that tire pressure.


I'll let you know if it ever happens.

The Michelins on there right now have almost 50,000 miles (getting pretty worn, tho) and the wear across the tread is 100% even-flat. The ride is great.

Originally Posted By: TheStig83
Do you replace your tires every 10,000 miles at that psi?


No, 35,000-45,000 is about what I get. I'm actually amazed that this truck is so easy on tires. I spend a LOT of time pulling a trailer, too.

 

[Bud]

3 over what door sticker states

 

[LeakySeals]

The tire serves as a shock absorber. Over-inflated the stress is at the rim and suspension. Something like that. May be a wise tail but My understanding was under-inflated is better snow traction?

 

[CR94]

Originally Posted By: SirTanon
Originally Posted By: Linctex
My 265/70R-17's say max 44 psi on the sidewall, that's where I run them. I don't care what the door tag says.


Welcome to blowout pressure when it gets hotter.
Not gonna happen. The factor of safety between maximum on the sidewall and blowout pressure is much larger than you assume.

 

[Rand]

Originally Posted By: HerrStig
Above 40 PSI in the New England pothole capital of the world will get you bent rims and bruised sidewalls.


Not sure how that happens.

low pressure = bent wheel
high pressure = tire damage, harder on suspension

high pressure would tend to protect the wheel more.

 

[RooflessVW]

I run ROW pressures. In the USA the door jamb says 40f 44r. Everywhere else is 38f 35r. Rides much nicer.

 

[901Memphis]

Barry (capriracer) hasn't posted yet, here's his site if you haven't seen it. He's a tire engineer

http://barrystiretech.com/

 

[Linctex]

Originally Posted By: TheStig83

What kinda vehicle are these on and what does the door placard say for psi? 44 psi is insane.


Doortag says 38, so I'm only 5-6 over.

 

[bubbatime]

When I went through the police academy driving class, they had two identical cars set up for us to drive. One car had 25 PSI in the tires, and the other car had 45 PSI in the tires. The car with 45 PSI tires drove like a track car and stuck to the track like glue. The car with 25 PSI tires sucked on the course, was MUCH slower, much less responsive, and flat out dangerous to drive. It was quite an eye opener and a life long lesson learned on the importance of tire pressure. I run 3-5 PSI over in every car I have.

 

[jorton]

Spec'd TP is 32 psi.

How would running 35 front and 30 rear in order to offset that squashed front and hard rear "look" affect safety, tire wear and fuel economy?

 

[THafeez]

My car recommends 29 on front and back which is comfortable and doesn't effect the already [censored] local mpgs so I keep it around there over breaks for work (close by, [censored] roads) and in the summer since the psis rise. Right now I'm keeping it at a cool 35 psi since it's mostly highway driving and I lose a couple psi here and there. Try to fill em up every week or so. Saw some mpg difference but I was driving like a grandma with some Techron in the tank so it could be a combo of all those things or none. I usually see an mpg boost after Techron, but I feel it's kinda artificial since the results go away after that tank is finished

 

[Nate1979]

Normally about 60psi in my Sierra 2500 but recommended is 75psi which is too high, only for loaded weight. Have it at the recommended 75psi right now because I had a ton of wood pellets in the back. This reminds me I need to drop them back down.