TV tire pressure - over-inflated by tire shop

Anthony Hitchings

Super Active Member
Silver Supporting Member
Mar 2, 2019
3,651
Oakland, California
Once again a tire shop has put too much air in my SUV tires, the door pillar placard says 33 psi, they put in 40 psi. It makes the ride harder and reduces road traction (when its oo bouncy there is less traction availale).

IMO - this is symptomatic of America becoming dumber by the day.

This practice is widespread in my experience. The worst was my Mazda auto shop - my poor little miat practically went skipping down the road to to overly-hard tires.
 

J Starsky

Super Active Member
Aug 3, 2017
1,210
East Central MN
What's the tire say on it? I'd follow the tire before the door sticker.

I didn't know my Suburban 2500 was @ 140ft lbs wheel lug torque until GM told me so. I had thought 125lbs was the 8-lug gospel, and I bought a new torque wrench to make the pulling easier. Good Times.
 

xxxapache

Super Active Member
Jul 30, 2008
4,382
140 ain't the 8 lug gospel, either. My F350 is 165 ft lbs.

As far as the OPs tires go, if he's running the stock size, I would go with the number on the door jamb sticker.
 

J Starsky

Super Active Member
Aug 3, 2017
1,210
East Central MN
140 ain't the 8 lug gospel, either. My F350 is 165 ft lbs.
RIGHT~! I guess that's my point. I used to work around 8 lugs that were actually ALL 125lbs, or that's what they had us inspect and pull to... Trailers, trucks, anying 1.5 ton or less was the preaching. I never thought to look up my 2001, I just figured GM is as GM does... Totally guess not. Worth looking at what the tire, or in my case what THE TRUCK and GM say, which is never my 1st move.
 

KeizerTrailer

Member
Aug 31, 2020
72
Keizer, OR
The pressures on the placard on most SUVs and passenger cars are set for comfort and not proper inflation for wear and traction. I worked in the tire industry for a short while and the low inflation pressures usually increase tire wear. I have worked at many a shop where we have found that many SUVs and half ton trucks have better, more even tire wear. Most customers have never even noticed a ride difference between factory set and our set pressures. Besides, the tires were not overinflated, most standard load tires are rated at 44psi. I run 40psi in my Wife's XC90 due to it being a lard ass and have noticed better tire wear than with factory recommended pressures. But to each their own.
 

Anthony Hitchings

Super Active Member
Silver Supporting Member
Mar 2, 2019
3,651
Oakland, California
well, I would think that in our litigous societey, installers would use the vehicle placard pressures.

I would also think that the mandated safey tests were performed at vehicle placard pressures.

the Load Application Table from TOYO (my tire manuf) says "For inflation pressure recommendations for the OE size, refer to the tire information placard or owners manual" - that seems pretty clear direction.

FYI - excerpt below is from the 37 page "Application of Load Inflation Tables" from Toyo.
1655933116230.png
 

Snow

Super Active Member
Jul 19, 2007
11,982
Ontario
That door placard is only relevant if you have o.e.m make/model/size of tire.. if you changed either of them (make/model/size) go with what the tire says..

I have never run any of my tires at the door placard pressure.. at minimum I run then them 5 psi above and up too 15 psi over..
 

Sjm9911

Super Active Member
May 31, 2018
11,730
Nj
That door placard is only relevant if you have o.e.m make/model/size of tire.. if you changed either of them (make/model/size) go with what the tire says..

I have never run any of my tires at the door placard pressure.. at minimum I run then them 5 psi above and up too 15 psi over..
Agreed , useless if you have changed your tires. I had a flat fixed on a lt tire, the inflated it to the P rated oem tires. No where near close. This was on my last truck. If they went by the tire pressure on the tire itself they were doing there job well.
 

Lug_Nut

Active Member
May 29, 2016
243
Mt. Wachusett area, MA
That door placard is only relevant if you have o.e.m make/model/size of tire..
True. The door jamb sticker is valid for the tires the vehicle manufacturer installed.
If you new tire has the same size (exactly, as in P225/75R16) and load rating as OEM - the door pillar pressure is still valid.
Not necessarily true. Some tires have different construction and different maximum cold inflation pressure ratings even though they are the same nominal size and have the same load rating at those different pressures.
example: Two different General Tire Altimax RT43, both 195/60R15, both load rated 88 (1235 lb.) both tread wear rated 600. One with a max cold pressure of 44 psi, the other with a max 51 psi.
Now what?
 

1380ken

Super Active Member
Nov 7, 2013
2,871
Mass
RIGHT~! I guess that's my point. I used to work around 8 lugs that were actually ALL 125lbs, or that's what they had us inspect and pull to... Trailers, trucks, anying 1.5 ton or less was the preaching. I never thought to look up my 2001, I just figured GM is as GM does... Totally guess not. Worth looking at what the tire, or in my case what THE TRUCK and GM say, which is never my 1st move.
I tighten my lugs with a cross wrench. Tight
 

Anthony Hitchings

Super Active Member
Silver Supporting Member
Mar 2, 2019
3,651
Oakland, California
True. The door jamb sticker is valid for the tires the vehicle manufacturer installed.

Not necessarily true. Some tires have different construction and different maximum cold inflation pressure ratings even though they are the same nominal size and have the same load rating at those different pressures.
example: Two different General Tire Altimax RT43, both 195/60R15, both load rated 88 (1235 lb.) both tread wear rated 600. One with a max cold pressure of 44 psi, the other with a max 51 psi.
Now what?
Same as for Toyo - go to manufacturer's website and look for their written guidance on adjusting pressures for non OEM tires. Toyo sure has a helpful website.
 

Anthony Hitchings

Super Active Member
Silver Supporting Member
Mar 2, 2019
3,651
Oakland, California
Side note:

loaded section width of tire at 40 psi = 247 mm +/- 1 mm

loaded section width of tire at 34 psi = 251 mm +/- 1 mm

6 psi does not change the tire's shape much
 

Lug_Nut

Active Member
May 29, 2016
243
Mt. Wachusett area, MA
Side note:

loaded section width of tire at 40 psi = 247 mm +/- 1 mm

loaded section width of tire at 34 psi = 251 mm +/- 1 mm

6 psi does not change the tire's shape much
Not what you can see, but it does have a great effect on the contact patch.
Less pressure puts less of the load on the center of the tread contact. This condition has a greater tendency for hydroplaning.
More pressure puts more of the load on the center, less on the sides. The chance of hydroplaning is less than with lower air pressure, but the steering/turning ability is reduced by the reduction of a flat tread contact.

Each vehicle, each tire and wheel combination, each load, will have its own idealized air pressure.
Taking the door-sticker recommended air pressure to obtain the vehicle manufacturer's compromise of ride quality/tire wear/noise/ as the be-all, end-all for any tire is foolish.
The same knee-jerk reaction to run at the tire maker's maximum inflation pressure regardless of tire load or operating conditions is no more sensible.

Each of you can determine the 'best' air pressure for your tires on your vehicle based on how and where you drive.
I've got my own 'best' and I'm not about to pretend that my air pressure setting has to be your air pressure.
 

Sneezer

Super Active Member
Aug 8, 2015
2,993
DFW, TX
I always go off the tire sidewall for pressure. Then again, I don't have a new car - all mine have gone through a couple sets of tires, and many had different pressures from the last.
 

neighbormike

Super Active Member
Gold Supporting Member
Oct 6, 2012
3,829
WI
Don’t (only) go off what the tire is rated for… look at the vehicle placard… just because a tire can “handle” 44 or 51 or 65 psi, doesn’t mean that is what’s best for the vehicle! That being said, 28, 29, 30 psi on the placard is pretty bogus. I would never go below 32psi except in an atv or lawn tractor lol
Note: sidewall pressure is the maximum pressure the tire is rated for - not anything to do with what the vehicle is rated for.
 




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