Tire pressure accuracy
Senior Member
Joined: 03-27-2008
Posts: 471
From: Blue Springs Missouri
I worked with Ammco/Coats when tire pressure monitoring first came on the market. I wrote several manuals dealing with tire changing, balancing, etc. on cars with TPMS installed. At the time, no manufacturer was including it on the vehicle, they were only aftermarket. Anyway, one of the things we covered in our manuals was that the system was best for monitoring the change in tire pressure and not necessarily the "actual" pressure in the tires. That was the point of the original systems: to help you monitor the pressure in your tires so that you were aware of any loss in pressure.
I've been flamed on this before, but trust me, I worked in this field at the beginning.
The current systems are far superior to those first ones, but the fact still remains that you should only rely on them to notify you of a tire going soft and not to give you "accurate" psi readings in your tires. Always use a good, reliable gauge to check the pressures yourself and maintain proper pressures.
Just my 2 cents. Flame resistant suit now engaged.
I've been flamed on this before, but trust me, I worked in this field at the beginning.
The current systems are far superior to those first ones, but the fact still remains that you should only rely on them to notify you of a tire going soft and not to give you "accurate" psi readings in your tires. Always use a good, reliable gauge to check the pressures yourself and maintain proper pressures.
Just my 2 cents. Flame resistant suit now engaged.
i would tend to agree that its there just to monitor .....
Senior Member
Joined: 01-02-2008
Posts: 1,529
From: Nashville, TN
True. Trade off here is that over inflated tires wear unevenly, just as under inflated tires do. Of course, the wear-out is different for the two, but it does shorten the effective life of the tire. Maintaining tire pressure at the tire manufacturers recommended pressure is the best way to get maximum tread life (depending, of course, on other factors such as proper balance, alignment and other related items).
Founding Member
Joined: 11-23-2007
Posts: 8,210
From: Texas
I go by what GM says. Correct pressures are on a yellow label located on the drivers door jam.
Senior Member
Joined: 08-06-2008
Posts: 1,761
From: Grand Haven, MI
True. Trade off here is that over inflated tires wear unevenly, just as under inflated tires do. Of course, the wear-out is different for the two, but it does shorten the effective life of the tire. Maintaining tire pressure at the tire manufacturers recommended pressure is the best way to get maximum tread life (depending, of course, on other factors such as proper balance, alignment and other related items).
Senior Member
Joined: 05-17-2008
Posts: 350
From: Indiana
I was getting real big differences in my stick qauges and my DIC, ended up getting a new digital air gauge, and was able to dial in the pressures right on the money (granted , the accuracy of the new one could be off a lil also)I compared my new gauge, the DIC and the couple of stick type gauges i had and end resultas was: the stick ones were WAY off(tires woulda been underinflated, one gauge was 8-10 PSI over what it really was!
)After all this, i realized one of the stick gauges was prob 25 yrs old!
(pitched them inna heartbeat 
)
Senior Member
Joined: 05-17-2008
Posts: 350
From: Indiana
Last set of tires i had installed on the truck, i noticed i had a tire that would go low(flat) in a 1/2 days time. during the couple of times to the tire dealer to get this taken care of (new tire), i was told that "someone" had put, or left , almost 50 PSI in the 4 tires(prob forgot to let out the air after setting the bead or something, or mebbe someone there had a way off gauge). Either way it rode a LOT nicer after they set the pressure to the sticker on the door.
Platinum Member
Joined: 05-09-2006
Posts: 6,805
From: "Upland" Mesa, Arizona
I think it needs to be said.....
The MANUFACTURERS TIRE PRESSURE RECOMMENDATION (as ChevyMgr, states, found on the sticker on the drivers door sill) is best for the overall performance of the vehicle. This considers the weight of the vehicle, amoung other things, for the proper PSI. This will allow the greatest contact of the tire to the road surface for maximum braking efficiency. GM provides this recommendation through vehicle testing and is calculated with a nominal driver weight (some of you are weigh (spelling intended) over the NOMINAL), a full tank of gas and 25 pounds of miscellaneous gear. However, this may have changed.
Over inflation (which provides a slightly "higher" tire) will round the tire and minimize thread contact with the road.....higher pressure, rounder tires...less contact. Conversely reducing tire pressure causes cupped or concaved tread to road surface patterns. Thus, also reducing braking efficiency.
Understand of course, as your vehicle weight increases, do to passenger or material, there is a necessity to increase tire pressure, ACCORDINGLY.
The TIRE MANUFACTURERS RATING, located on the side of the tire, is based on several different vehicle applications, for the tire, and/or the increased content load of the specific vehicle.......in which case, the maximum should not be violated.
At least that is what was told to me by tire engineers when I worked for "The General".
It amazes me that owners will spend a thousand dollars to increase braking efficiency on new rotors and pads and then under or over inflate a tire which provides a negative dynamic. The new brake equipment is only as good as the critical contact to the road.
The MANUFACTURERS TIRE PRESSURE RECOMMENDATION (as ChevyMgr, states, found on the sticker on the drivers door sill) is best for the overall performance of the vehicle. This considers the weight of the vehicle, amoung other things, for the proper PSI. This will allow the greatest contact of the tire to the road surface for maximum braking efficiency. GM provides this recommendation through vehicle testing and is calculated with a nominal driver weight (some of you are weigh (spelling intended) over the NOMINAL), a full tank of gas and 25 pounds of miscellaneous gear. However, this may have changed.
Over inflation (which provides a slightly "higher" tire) will round the tire and minimize thread contact with the road.....higher pressure, rounder tires...less contact. Conversely reducing tire pressure causes cupped or concaved tread to road surface patterns. Thus, also reducing braking efficiency.
Understand of course, as your vehicle weight increases, do to passenger or material, there is a necessity to increase tire pressure, ACCORDINGLY.
The TIRE MANUFACTURERS RATING, located on the side of the tire, is based on several different vehicle applications, for the tire, and/or the increased content load of the specific vehicle.......in which case, the maximum should not be violated.
At least that is what was told to me by tire engineers when I worked for "The General".
It amazes me that owners will spend a thousand dollars to increase braking efficiency on new rotors and pads and then under or over inflate a tire which provides a negative dynamic. The new brake equipment is only as good as the critical contact to the road.
Senior Member
Joined: 08-06-2008
Posts: 1,761
From: Grand Haven, MI
Thanks Snoopy, I didn't think that a tire mounting on the appropriate wheel inflated over the door label pressure, but under the tire manufacturers max would "round the tire". I guess that makes sense.
Soooooo, since I am usually in my car alone, should I be inflating the drivers side more than the passengers side Just kidding.
What about when you change tires and tire brands? Do you still use the door label, or what on the sidewall
Soooooo, since I am usually in my car alone, should I be inflating the drivers side more than the passengers side
Just kidding.What about when you change tires and tire brands? Do you still use the door label, or what on the sidewall
Founding Member
Joined: 11-23-2007
Posts: 8,210
From: Texas
No.