Whats with the crazy high PSI in tires?

[Mitsu3000gt]

I'm just wondering if there's a reason we keep getting cars returned to us with crazy high PSI in the tires.

We picked up my Mom's brand new Murano from Fish Creek Nissan, and it had 47 PSI in all 4 tires.

My dad got his car back from Tunerworks today, and it had 45 PSI in all 4 tires.

Always about 15 PSI over factory spec.

Is there a practical reason for this I don't know about? It's not a big deal because I always check the pressures and fix them, but I'm curious if there is a reason some shops seem to be doing this? I'm thinking it might be more of an issue for someone who never checks their tires (most people don't).

[VetteRacin]

maybe their gauges are out lol

[sr20s14zenki]

Accelerate tire wear? Then you come back and spend
Money

I thought only the sleezy places did that.

[FiveFreshFish]

Perhaps your gauge is out of calibration?

[AE92_TreunoSC]

Often dealer techs run 5psi over spec to prevent the TPMS light from coming on during cold snaps.

I don't know any tech's that run over 40psi on any passenger car.

The Murano is shipped with 44psi factory and is often exchanged for nitrogen, then set to factory spec.

Are you using a pen gauge? Reading the murano's tire pressure read out?

[Sugarphreak]

...

[Mitsu3000gt]

I'm using a Blue Point digital tire pressure gauge/inflator I bought at Snap on. It was $150 or so, and I don't have any reason to believe it's inaccurate. I double checked with an el-cheapo reader from Canadian Tire and got the same reading of mid-high 40 PSI.

I'm not upset or anything, just curious if there was an actual reason this was happening, or if it's forgetful shop people. It was a 5 min fix, but I was thinking more of people who never check their tires, ever - they'd be driving around at nearly 50 PSI all day long.

[EK 2.0]

My obvious question to you...are you checking them when they have just been driven on or??...

[Mitsu3000gt]

Originally posted by EK 2.0
My obvious question to you...are you checking them when they have just been driven on or??...

Nope after it's been sitting for a while, but in both cases the drive was only around 10 min anyways, and I really doubt it would raise it 15 PSI above factory even if I checked them right after the drive (which I didn't).

[AE92_TreunoSC]

I'm glad you check your pressures and that you are educated in knowing they shouldnt be set to the max pressure on the sidewall but rather what is in the manual or doorsill.

It baffles me that people don't know what the pressures should be set to. The average consumer just wants them to have air in them and for the warning light to remain off.

What I would suggest is to maintain your own pressure and advise the shops to leave the pressures. Or better yet, vocalize the problem and make sure its addressed.

[HomespunLobster]

I worked in a tire shop for a few years. It's crazy when you get a customers car in, with factory supposed to be at 35 PSI, and i'd have to use a high tire pressure gauge to get a reading. Had tires come in around 100 psi.

Fill it till it's round!

[RickDaTuner]

Originally posted by Mitsu3000gt
I'm using a Blue Point digital tire pressure gauge/inflator I bought at Snap on. It was $150 or so, and I don't have any reason to believe it's inaccurate. I double checked with an el-cheapo reader from Canadian Tire and got the same reading of mid-high 40 PSI.

I'm not upset or anything, just curious if there was an actual reason this was happening, or if it's forgetful shop people. It was a 5 min fix, but I was thinking more of people who never check their tires, ever - they'd be driving around at nearly 50 PSI all day long.

I have this gauge as well. they all tend to be 1.5 psi out. this gauge also calibrates itself every time you turn it on. so yeah its accurate.

I suspect like other have stated that the gauges they are using are out. a single drop will throw the pressure spring out on a dial gauge, and lack of graphite lube will make the pen style gauges stick.

[know1edge]

Yea I would say they were just aired up to the maximum spec on the tire, and instead of correcting the ~3 psi they just left it.

[Toma]

I thought everyone that wants better mileage runs minimum 40 psi.



Be careful though, if you are the unfortunate owner of a VW, you'll kill the balljoints faster

[bspot]

It's a great way to have tires with no centre tread left and tons of outside tread left.... oh well, in the garbage they go!

[Twin_Cam_Turbo]

Overfill them 5 or so psi so the centers wear with normal driving and the shoulders when you corner im kidding of course.

[tirebob]

Tires should not be run at the maximum pressure shown on the sidewall for any sort of regular use whatsoever, but that said, air pressure is one of the quickest, simplest, effective ways of tuning your vehicles handling. No one setting is best for everything. I personally like a little firmer than the stock recommended setting for my Accord, but on other vehicles I have run slightly under the listed pressure. It also varies a bit tire to tire for me... Generally though, I am not varying much more than a few PSI one way or the other from the factory recommendations based on use...

[EG STyLeZ]

I find that my cold tire pressure can vary by up to 5 psi just from the change in temperature throughout the day. Do you guys go by your recommended tire pressure at the higher or lower temperature?

[star-k]

Manufactures rate cold, set your pressures based on cold.

[rage2]

The door sill sticker recommended pressures are usually on the high side, as it's the factory recommended setting for full load, at top speed. The chances of you running top speed with every seat taken by a 200lb person plus shitloads of luggage is rare, so you want to tweak it down based on your usage.

Most shops that set your tire pressures just follow that sticker, hence, it's so damn high.