tire pressure

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Princess Valiant

Princess Valiant

A.K.A. Rainy Day Auto
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every tire has a max. tire pressure imprinted on the side wall ....i notice most newer ones are 44psi.

is it best to set the pressure at the max or is there a percentage of the max. that would be better?

it would seem that if the tire is more inflated through its life the center track is more likely to wear than the edges and if its inflated less through its life then the opposite ....the edges will wear before the center track......so is there an ideal pressure that will make it wear even across the center and edges.

also it would seem that front tires are better inflated more so the center wears faster bcoz if you happen to have a slight toe in or toe out problem, the tire can kinda "slide" off the center. so if that was the case ...the rear tires would best be inflated less for more edge track contact to the road, this way when you rotate the tires it will even out the wear over the center to the edges.

if that would be the case then you would have to watch the wear especially of the fronts for signs of an over positive or over negative camber bcoz the camber would then be the factor to cause rapid tire wear.

any thoughts?
 
for highway use, i believe the numbers printed on your car would be for the weight of the car and type of tires (probably bias ply originally). might even say 24 lol.

typically you put in 32lbs for bf goodrich radial t/a's if you run those

for drag racing your slicks ... that's a whole different animal
if you 4x4 and have mud boggers, again totally different
if you autocross, a whole nother story lol

but if you want to make sure you can put chalk lines on the tires, do some driving and check if the chalk is wearing evenly

also this is from the bf goodrich site:

WARNING: Serious or fatal injury may result from tire failure due to underinflation or overloading. To ensure correct air pressure and vehicle load, refer to vehicle owner's manual or tire information placard on the vehicle. Serious injury or death may result from explosion of tire/rim assembly due to improper mounting. Only tire professionals should mount tires and they should never inflate beyond 40 psi to seat the beads. Before mixing types of tires in any configuration on any vehicle, be sure to check the vehicle owner's manual for its recommendations.
Inflation pressure increase must not exceed the maximum pressure branded on the tire sidewall. When a customer requests a replacement tire with a lower speed rating than the original equipment tire, you must clearly communicate to him or her that the handling of the vehicle may be different, and that its maximum speed capability is limited to that of the lowest speed-rated tire on the vehicle. Exceeding the lawful speed limit is neither recommended nor endorsed.
For high-speed driving, additional inflation pressure and possibly reduced tire loading and/or upsizing is required. In the absence of specific recommendations by the vehicle manufacturer, use the following guidelines based on those in the European Tyre and Rim Technical Organization Standards Manual.
For speeds over 160km/h (100 mph), load and inflation must be adjusted according to the table below.
T-Speed Rated Sizes:
Maximum Speed (mph) 100 106 112 118
Inflation Increase (psi) 0.0 1.0 2.0 3.0
Load Capacity (% of max.) 100 100 100 100
​
 
My valiant is very light at 2.747 lbs, I keep my radial tires inflated low for daily driving to take care of my suspension, Like a basket ball that has more air in it , it will beat the chit out of your shocks and control arms.
27lbs for my little car, now! If I hit the HWY I jack them up to 33 all around for gas milage, and when I get to my destination I soften them up for a smooth ride in town and on gravel roads. These little cars if set up right do not use up tires, I have well over 7.000 miles on a set of new radial tires and I can't see any wear, but as soon as I do I will rotate them , thus all four corners are all the same size.
One more trick, inflate your tire till you can not slide an envelope under the tread line, if you can, back off the air pressure
 
i dont think we can go by the door jamb decal anymore.....tires have come a long way and i dont think you can buy bias ply anymore and if you could ...why.

the modern tires are max. pressure on 44 psi. so if you guys are settting them in the 20s thats ....way too low.

new tires can by deflated without even looking flat....the new tires are amazing compared to what came on these cars originally.

for this discussion i was talking about new tires that are available at common retailers in 2013 .....not so much antique 32 psi or non-existant bias tires from 1965.
 
I always run my tires at the recommended pressure. That way if I need to bring them back I can assure them that they were proporly inflated. I am also a fan of nitrogen for tires. Most of my tires come from Costco who use nitrogen all the time.
 
RaniDart70 said:
i dont think we can go by the door jamb decal anymore.....tires have come a long way and i dont think you can buy bias ply anymore and if you could ...why.

the modern tires are max. pressure on 44 psi. so if you guys are settting them in the 20s thats ....way too low.

new tires can by deflated without even looking flat....the new tires are amazing compared to what came on these cars originally.

for this discussion i was talking about new tires that are available at common retailers in 2013 .....not so much antique 32 psi or non-existant bias tires from 1965.
Click to expand...


hmmmm well what you could do.... let's say your car weighs 3,500 lbs

and you want to use brand X tires, and have a size that you are putting on.

you find a current car that weighs 3,500 that uses that tire and find out what the door sticker says

that should give you a close approximation to a safe inflation range.
 
newer tire
 

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1968dartman said:
I always run my tires at the recommended pressure. That way if I need to bring them back I can assure them that they were proporly inflated. I am also a fan of nitrogen for tires. Most of my tires come from Costco who use nitrogen all the time.
Click to expand...


do you go with the tire recommendation or the decal on the car?
 
moparlover said:
hmmmm well what you could do.... let's say your car weighs 3,500 lbs

and you want to use brand X tires, and have a size that you are putting on.

you find a current car that weighs 3,500 that uses that tire and find out what the door sticker says

that should give you a close approximation to a safe inflation range.
Click to expand...



thats an idea but qould the different handling between the two cars change anything?
 
RaniDart70 said:
ok, so if we have a recommendation on the tire which arguably is made for a new car and a recommendation on the car which takes that specific car's weight into consideration .....then where is the happy medium?
Click to expand...

no that is not a recommendation on the tire. that is the max pressure rating... if you go over that it will have a high chance of blowing out.

most cars, if you go look at the door stickers, are about 65% of the max pressure as the recommended pressure.

actually, the tire manuf. do not give "recommended pressure" they refer you to the owners manual for your car
 
moparlover said:
no that is not a recommendation on the tire. that is the max pressure rating... if you go over that it will have a high chance of blowing out.

most cars, if you go look at the door stickers, are about 65% of the max pressure as the recommended pressure.

actually, the tire manuf. do not give "recommended pressure" they refer you to the owners manual for your car
Click to expand...


ok i get it now. :D
 
Always go by the pressure sticker on the door(if there is one). That is what the manufacturer of the car test with and recommends. The same size tire run on different cars will have a different factory pressure spec. The max pressure on the tire is only there telling you that is the maximum you can run in that tire.
If you go to tirerack.com and fish around you can learn good stuff.
YES bias tires are reproduced for guys like me that PREFER the bias look on our old cars....my bias E-70 14s are supposed to run 32psi.
 
RaniDart70 said:
do you go with the tire recommendation or the decal on the car?
Click to expand...


I always go with what the tire manufacturer says not the door jam sticker. As I see it the manufacturer knows what their tires require much better that any car manufacturer. JMO
 
moparlover said:
no that is not a recommendation on the tire. that is the max pressure rating... if you go over that it will have a high chance of blowing out.

most cars, if you go look at the door stickers, are about 65% of the max pressure as the recommended pressure.

actually, the tire manuf. do not give "recommended pressure" they refer you to the owners manual for your car
Click to expand...

Actually there is a MUCH HIGHER risk of blow out if the tire is run underinflated because that causes a lot of heat. That is why newer cars all have the tire pressure sensors in the valves to warn you if a tire is LOW in pressure.
 
I always go 4 PSI below the max pressure on the tires, and rotate them every other oil change. Never have had a problem.
If you recall some 10-15 years when Fords were having the rollover accidents, it was from the tires being underinflated per the tire manufacture specs. Ford had them at a lower psi for a more comfortable ride or something. If I remember correctly...
 
73 Dart Swinger 318
28 in the back 32 in the front. (or whatever makes the tire wear flat across the full tread)

I recently had tires made by Kumho on my Nissan pickup that the normal recommended pressure was 60lbs.
I told them I didn't want it to feel like it was running solid rubber tires, and they told me that they feel like any other tire inflated to 35.
They did.
 
TrailBeast said:
73 Dart Swinger 318
28 in the back 32 in the front. (or whatever makes the tire wear flat across the full tread)

I recently had tires made by Kumho on my Nissan pickup that the normal recommended pressure was 60lbs.
I told them I didn't want it to feel like it was running solid rubber tires, and they told me that they feel like any other tire inflated to 35.
They did.
Click to expand...


WOW, were those P-series or LT series tires ?

i found a hankook ....low profile passenger car tire just now that had max. 51 psi on the tire.

i know LT series are usually way different ...my uncles F-250 has huge LT tires and those say max 80 psi ...but they are on 8 lug rims ....prolly weigh more than me.....scary
 
I always set mine to about 32 psi cold drive and warm them up so they are at there operating psi and drive in something that will stick on the tire or make marks on the ground and see where the tire is actually touching the ground and try to get them to where the entire tire is making contact with the ground I never go to max because that is where the tire can carry the most load and without the max load on them the center will only be making contact therein wearing faster.
 
i never go by the door jam sticker on my old stuff. the door has no idea what kind of tread im running LOL !!!!!. i always go by the tire . in my case thats mostly 35 psi

my 2 pennies anyway

my snow tread is at 25 psi for the duster
 
TrailBeast said:
73 Dart Swinger 318
28 in the back 32 in the front. (or whatever makes the tire wear flat across the full tread)

I recently had tires made by Kumho on my Nissan pickup that the normal recommended pressure was 60lbs.
I told them I didn't want it to feel like it was running solid rubber tires, and they told me that they feel like any other tire inflated to 35.
They did.
Click to expand...

That depends on the ply of the side walls and the softness of the rubber they use. Which will affect the mileage you get out of them. The softer the better traction the more mileage wear the shorter they will last the( more friction). The firmer rubber supposedly the longer they last (less friction).
 
RaniDart70 said:
i know LT series are usually way different ...my uncles F-250 has huge LT tires and those say max 80 psi ...but they are on 8 lug rims ....prolly weigh more than me.....scary
Click to expand...

YES, my Dodge 2500 uses 10 ply LT tires with max 80psi. Door sticker says 60psi in the front, 70psi in the rears. This is exactly what I was saying earlier. Different car manufacturers and different uses using the same tire but different PRESSURES are recommended!!!!!!!!!!!! Believe me, UNLESS you have a test lab to test the thousands upon thousands of situations and circumstances, go by the RECOMMENDED pressures.....enough said?
 
BB-Dave said:
Always go by the pressure sticker on the door(if there is one). That is what the manufacturer of the car test with and recommends. The same size tire run on different cars will have a different factory pressure spec. The max pressure on the tire is only there telling you that is the maximum you can run in that tire.
If you go to tirerack.com and fish around you can learn good stuff.
YES bias tires are reproduced for guys like me that PREFER the bias look on our old cars....my bias E-70 14s are supposed to run 32psi.
Click to expand...


thats very interesting.....are the re-pop bias tires made out of original materials or modern compounds ?

i was amazedto find that in new tires the amount of real rubber in them is nothing like it used to be .....its a synthetic now .....prolly why they dont want ppl burning tires ....toxic gases from the chemicals that natural rubber would not have.
 
RaniDart70 said:
thats very interesting.....are the re-pop bias tires made out of original materials or modern compounds ?

i was amazedto find that in new tires the amount of real rubber in them is nothing like it used to be .....its a synthetic now .....prolly why they dont want ppl burning tires ....toxic gases from the chemicals that natural rubber would not have.
Click to expand...

Burning tires had always been bad....but fun :D
 
The max pressure on the tire is there to keep you safe. The tire companies test the tire to failure rate then stamp the tires with max pressure they figure is safe.
It's probably not the failure pressure. I'm sure they have a buffer amount they use that way they don't get sued.
 
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