Tire pressure question.

[Phoenyx]

OK, so I got a new set of Nokian tires recently. And I went to check the tire pressure today and they were all at 45psi. That seemed a little high to me. I have always put my tires to 35psi. I thought it was kinda funny that the tire shop (Kal Tire) would over inflate them. So I stopped by and asked them what pressure the tires should be at. They told me that it goes by the car not the tire. And that I should just go by what it says on the factory door sticker.

But then I was thinking. Will it make a difference that I ditched the 14" rims and put on 15" ones with 195/60/15s. And then to make things worse when I went to check the sticker, and realized that it was gone.

So can you guys tell me what your stickers say? 14" ones and you guys that have factory 15" ones.

And if there's any tire experts out there. What tire pressure do you think I should use?

 

[midwestls]

I use to work at a Valvoline and our company made us go by the factory recommendation inside the door, although some cars have them in different places like an opposite or rear door jamb or in the gas door. Me, I've always ran between 32 and 35 on the street. If you need me to I can go out and look at my car for you tommarow. Let me know.

 

[84GP455]

When i worked at a garage i just looked on the tire itself. There is a psi rating on every tire on the sidewall. It may be a little small but it is there. I never understood why anyone would look at the sticker on the door, because my car for instance is 24 years old and i don't think that the tires would be original at that point and also like you did i changed the size from a 14" to a 15" so how could the psi be the same for both? I don't think the sticker on the door is useful unless the car is say 5 years old or less. Look at the tire, the manufacturer states what psi to inflate them to, not the car! Some low profile tires do take 45 psi so it could be right but if i were you i would look on the tire itself. I use nitrogen in my tires, it's better than air. Nascar uses Nitrogen also so that's good enough for me!

 

[midwestls]

http://www.tirerack.com/tires/tiretech/ ... p?techid=8

http://www.sportcompactcarweb.com/tech/ ... index.html

the second one is a little more specific

 

[dan2286]

When i worked at a garage i just looked on the tire itself. There is a psi rating on every tire on the sidewall. It may be a little small but it is there. I never understood why anyone would look at the sticker on the door, because my car for instance is 24 years old and i don't think that the tires would be original at that point and also like you did i changed the size from a 14" to a 15" so how could the psi be the same for both? I don't think the sticker on the door is useful unless the car is say 5 years old or less. Look at the tire, the manufacturer states what psi to inflate them to, not the car! Some low profile tires do take 45 psi so it could be right but if i were you i would look on the tire itself. I use nitrogen in my tires, it's better than air. Nascar uses Nitrogen also so that's good enough for me!

That rating on the tire is the max psi that can be put into the tire safely. The rating on the door is not just for factory tires. If you look at the tires that came with the car when new I guarantee that the psi that it says on the tire is not the same as the one on the door. The psi that the vehicle manufacture recommends is to get the most out of suspension parts, tire wear, fuel economy, etc.

 

[Blake442]

The numbers on the tire are for maximum payloads. Sure, it might say 55 psi max, but I'm sure as hell not going to drive around everyday with it set at that...

Just put them all at 35 psi and forget about it.

 

[DrRansom442]

This is how that whole Ford Explorer tire recall got ugly. Ford said one thing. Firestone said another and they conflicted. Both had investigations that they openned with the NHTSA reguarding the blow-out/roll over hazards but no one could decide who was in the wrong and who should take responsiblity.
IMHO, The manufacture does all the research reguarding what tires should be on the car. What speed rating. What wear rating. Basic design (i.e. an all-terrain tire on a Jeep). Many people (and the tire resellers are just as guilty) just buy "a set of tires" and don't take most of these things into consideration .... just as long as it's round and holds air.
Most "passenger tires" exceed the needs of most applications and as such a recommended inflation and a max inflation are both labelled on tires. As well as other ratings.
You should go by O.E.M. specs. If the tires you are looking at don't fall in that range - you need to look for some that do. In the event the wheels are no longer O.E.M. this likely makes the manufacture's specs obsolete and you should make sure the wheel maker has no particular specs reguarding load ratings and tire selection.
When in doubt 35 psi is pretty much a "standard" and I don't know of GM specifying otherwise on a "passenger" car application (truck tires yes, but I don't think I've seen a different spec for a "passenger" car). I usually run mine at 40 psi.
Never exceed the safe limits of the tire and never put a tire that doesn't meet the O.E.M. recommendations and you should be fine. Aftermarket wheels - I'd always glance over their recomendations - just to make sure things are harmonious.
I can think back to the days of "mag wheels" and how many people fail to retorque the rims after they seat. This led to wheel damage. Funny tire wear. It led to wheels coming off while driving down the road ... none ideal and are key reasons you don't see many wheels that require "mag" washers these days.

 

[megaladon6]

unless you are using the OEM tires, there is no answer. i have nokian rsi snows on my daily driver--vw jetta-- and my usual method of 5psi below max is WAAAAAY too much. it winds up giving me a very stiff ride. they go that high (50psi) because they're high load rated. i've found 40psi to work well with them, but i also "tune" the pressure for the best grip.

 

[Phoenyx]

Wow thanks for all the info guys.

Well if it matters I am just running stock steelies on the car. My sticker off the car is gone. And all the tires say for inflation is between 30-50psi.

So I think I'll just run them at 40psi and go from there.

Oh and since I am just running Nokian (not a performance tore) I am just looking for a psi that will make the tires last as long as possible. After winter I'm gonna be getting another set of stickier tires to run on the rear for better traction.

 

[shotgun]

Here is how I get my starting point.

Look at the side of the tire for max pressure/#.

I checked my tires 1650# @ 45 psi max

Divide 1650 by 45 , rounds to 37.

So each psi of air supports 37#.

Now the car.

Say 4000# with 55/45 weight distribution or 2200# front tires/1800 rear tires.

Since each end hopefully has 2 tires 🙂 ,divide that number in 1/2.

Each front tire is supporting 1100# each rear tire 900#.

Now divide each number by the 37 from above.

1100/37= rounds to 30
900/37= rounds to 24

This is your starting point and gives a nice plush ride.

Remember, this is a starting point, don't ride around with 15# if that's what you come up with.

You most likely will end up going up a few pounds , which is fine, but keep the ratio the same.

Try 32/26 or 33/27 etc

Another old school trick is take grease pencil and mark the tread around to the face of the tire in a couple of spots. Drive the car like you normally would, you can "see" how much tread is on the road and adjust from there.

That's from my rally days.