Tire Inflation Tables Work

[Mr_D]

Amazing isn't it!!!
The tire companies actually know what pressure you should run for a specific weight!! Don't need to second guess them or follow you cousins ex boyfriend advice.
Tire brand, model, size and weight carried, look it up in the charts and you're done!

[Tireman9]

Originally Posted by Mr_D

Amazing isn't it!!!
The tire companies actually know what pressure you should run for a specific weight!! Don't need to second guess them or follow you cousins ex boyfriend advice.
Tire brand, model, size and weight carried, look it up in the charts and you're done!

As long as people remember that the inflation in the tables are the minimum inflation. If you insist on running the table inflation based on the measure load you will probably need to adjust your inflation every day as ambient temperature changes, or you may be underinflated.

[MRUSA14]

Originally Posted by OverDo

Crasher,
Thanks for the usable info. I try to set the cold (~70 deg. F) temps at 5-10 PSI below the pressure/load table recommendation. All the tires will pick up 10-15 PSI pretty quick and I like the ride and bigger contact patch that a correctly loaded tire gives. Most rubber failures are from high temperature generated from excessive flex (low pressure or overload).

Setting the tire pressures BELOW the recommended inflation is both dangerous and absurd. Excessive flexing is caused by low tire pressure. If you underinflate your tires you are asking for a tire failure. Tire companies will refuse warranty claims on any tire that has ever been run underinflated.

[garyre]

I run TPMS on all my tires and have found that the temperature will increase 10-15 deg once running. Other factors that add to the variables are altitude, outside temperature, asphalt road temperature and sun direction during heat of day. Finding the sweet spot for proper inflation may include adjustment from time to time depending on conditions.

[kf6ybl]

Originally Posted by Tireman9

There is no "right " temperature. "Cold" means not warmed from the sun and not driven ofthe last 2 to 3 hours. I would not listen to those that are confused about what Ambient temperature means.


You might read THIS post from an engineer with 40 years experience designing tires for Trucks, cars, pickups and Indy race tires.
You could listen to someone who has driven around a lot and thinks this qualifies him to contradict tire engineers and the US Tire & Rim Association.
You decide.

Wow, thanks for the link and info! I went to the website and there's a wealth of tire related info, enough to make your head spin!

[Tireman9]

Originally Posted by garyre

I run TPMS on all my tires and have found that the temperature will increase 10-15 deg once running. Other factors that add to the variables are altitude, outside temperature, asphalt road temperature and sun direction during the heat of the day. Finding the sweet spot for proper inflation may include adjustment from time to time depending on conditions.

Yes, tire temperature and inflation can be affected by many things. BUT you should only be adjusting pressure when the tire is "Cold".

Elevation can affect pressure but unless you are driving to the top of Everest I would not worry.


The pressure listed in the tables is the MINIMUM you should ever use. I suggest you add 10% so you are not chasing your tail every morning when the temperature changes 10F. Tires can tolerate a few extra psi and that increase due to the operation is expected.


Don't make more work for yourself.


Tire pressure in Not Rocket Science.

[DryCreek]

Originally Posted by Tireman9

Except increased inflation will give better steering responsand better fuel economy and possible better durability.

Better durability? I'm having trouble seeing that aspect. If you are only effectively using 1/2 to 2/3 of your available tread footprint, how is wearing the center out going to give you better durability - unless you run the last third of tire life underinflated to even-out the wear?

[Tony Lee]

So what if you got a little extra center wear. You are going to replace RV tires on age anyway.

Ride harshness, reduced braking efficiency, poorer steering are all good reasons to get the pressures correct according to the load. Always best to note what the tyre manufacturers specify and ignore any other advice that is contrary.

BTW tire fitters put either 100psi or max sidewall pressure in because that doesn't take any brainpower to do it. Same reason they use a big rattle gun instead of a torque wrench.

[Mr_D]

On my rig if I run the chart pressure for my drive axle then lift the tag that transfers all the weight the tags normally carry (could be up to 14,000's add'l) to the drive tires which overloads them. Then what?

[Crasher]

Originally Posted by Mr_D

On my rig if I run the chart pressure for my drive axle then lift the tag that transfers all the weight the tags normally carry (could be up to 14,000's add'l) to the drive tires which overloads them. Then what?

I had the same question as I have a similar condition when I dump with a heavy trailer tongue. However, it is always below 10-15 mph and only for a few seconds, so I don't think any harm comes from it. You would have to run for some distance at highway speeds to heat up the drive tires to where damage could occur. Not likely to happen.

[OverDo]

There are two different pressure / load criteria. One is the allowable load at the maximum cold inflation pressure. I other words never put more pressure inn the tire no matter what the load is.

The other is the tires ability to carry a particular load at a particular pressure. Not a "cold pressure" but pressure period. The tire is simply a rolling air spring. As long as the pressure is met, the load can be safely applied at highway speed. No reason to have the highway pressures 20 psi over what the tire needs to carry its load. My rear tires need 95 psi to carry the load. I start them at 85 psi. They always end up at 100-105 psi after a few miles. Fronts need 115 psi to carry the load. I start them at 105 psi. They are always 120-125 psi after a few miles. When I started them at the 115 psi, they were over 135 psi warmed up and are obviously over inflated when you look at the profile. The ride is noticeably better at the lower pressures and still within the design limitations of the tire.

[CoachStreamr]

What do long haul truckers do? Do they check tire pressure all the time? I'm curious.


I am also curious why a place like Cummins (where we get our engine/suspension maintenance) inflate to the max psi listed on the tire. I asked about that and they said this is what they do and have always done.


.

[Crasher]

Originally Posted by OverDo

There are two different pressure / load criteria. One is the allowable load at the maximum cold inflation pressure. I other words never put more pressure inn the tire no matter what the load is.

The other is the tires ability to carry a particular load at a particular pressure. Not a "cold pressure" but pressure period. The tire is simply a rolling air spring. As long as the pressure is met, the load can be safely applied at highway speed. No reason to have the highway pressures 20 psi over what the tire needs to carry its load. My rear tires need 95 psi to carry the load. I start them at 85 psi. They always end up at 100-105 psi after a few miles. Fronts need 115 psi to carry the load. I start them at 105 psi. They are always 120-125 psi after a few miles. When I started them at the 115 psi, they were over 135 psi warmed up and are obviously over inflated when you look at the profile. The ride is noticeably better at the lower pressures and still within the design limitations of the tire.

I don't know where to begin to respond to your method. I've just never heard of anyone purposely starting with underinflated tires. Why do you suppose the tire manufacturers load charts specifically state that for a given load, they have a COLD INFLATION value that is the minimum needed to carry that load?

[Crasher]

Originally Posted by CoachStreamr

What do long haul truckers do? Do they check tire pressure all the time? I'm curious.


I am also curious why a place like Cummins (where we get our engine/suspension maintenance) inflate to the max psi listed on the tire. I asked about that and they said this is what they do and have always done.


.

Because the truck driver and Cummins are not concerned with the quality of the ride. You could inflate to the max on your tires too and run with it. But, I'll bet you won't like the ride