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Discussion Starter #1
My first experience with Load E tires, and I didn't find a specific answer in the manual or archives, so...


The tire sidewall states a minimum of 55psi, and a max of 80psi. What pressures should be used for around-town non-towing, and for towing (6000lb tag)? 80psi seems awfully high, but I don't want to damage the tires by underinflating either...


Thanks in advance!


Mark
 

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For around town I use 65 front and 55 back. You need the extra in the front because of the diesel.


Chilly
 

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GM takes the "You're not going to sue me because the average person does not know how to maintain their vehicle" stance.


It's unfortunate but we live in a society that " When I am stupid, I blame (sue) someone."


So GM gives the Maximum load ratings so you do not sue them when you have a blow out because you overloaded the weight for the air pressure rating of the tire.


From looking at the tire manufacturers loading sheet and my driving and loading habits I finally settled on:


Around town:
Front = 55 lbs
Rear = 50 lbs


When I am towing:
Front = 55 lbs
Rear = 65 lbs



Hauling:
Depends what I am hauling.
Example:
80 lbs all around with the back loaded with stone.


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Edited by: JohnnyO
 

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Well stated JohnnyO
 

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May be all wet here, but I thought the info was on the drivers door jamb? Too wet to go out and look for you right now...LOL


I run 55 all around whem empty and air up to 75 front 80 back when planning a tow.


80 empty = rough ride





Good Luck
 

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My alignment tech put 60 all the way around after aligning my front end. He also told me to rotate every 6k or so. I jack up the rears to 80 when pulling.
 

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The 04 door stickers says 60 front and 80 rear.


Since the front end is only rated to 4500#, I wouldn't go much over 60 in front since that is above the load capacity of the tire.


The rears need pumped up to get the load capacity or go to 265 and get a better ride w/ less air pressure.


We usually throw 100+ bags of bean seed (50# ea) and 110 gal. of fuel in the back of our trucks and I now the F-I-L doesn't add air just drives it.Edited by: Dmax Tim
 

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Dmax Tim said:
The 04 door stickers says 60 front and 80 rear.

That '04 diesel motor must be heavier
. The '03 door jam says 55 #'s in the front, 80 #'s in the rear.
 

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Discussion Starter #10
Thanks for the info guys, I know what to do now.



Mark
 

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The load sticker does state 55 front 80 rear. Most load E tires state 80 PSI max to achieve max load capacity. My truck came with Fierstone steeltex load E 245/65 R16. At 17000 miles they were completly shot. Tread bars showing and tread blocks pulling away from the carcass. I atrribute alot of this to improper air pressure. I ran the stated 55F and 80R. I replaced the firestones with Bridgestone Duler Revos. 265/75 R16. They guys at the tire shop insisted I ran the stated air pressure. They did tell me to bring it back at 4000 miles and we would re-adjust. Taking measuements across the tread in 4 spots showed that the front tires needeed to be raised and the rears needed to be lowered. I am now running 65F and 55R. This is with a camper shell and 200 lbs. of gear. I also tow a single axle trailer that weighs 2500 LBS. fully loaded over 75% of the time. I will remeasure the tread depth and let you know in another 4000 miles. I can tell you that after raising the front end 3/4" via torsion bar adjustment and changing the air pressure the truck has never driven better. If you do raise your truck be prepared to have it aligned and have the headlights realigned. You will also throw off your gas gauge. The warning use to come on at 3 gallons and now it comes on at 1.5 gallons.
 

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I run 65 psi all around empty and raise the rears as necessary when loaded or towing. 55 psi in the fronts is too low and there only to reduce "ride harshness" complaints at the expense of the tires. Running the fronts at that pressure will literally destroy your tires in about 1/3 of their normal wear-life because of the engine weight on our vehicles.
 

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Bronco said:
My truck came with Fierstone steeltex load E 245/65 R16. At 17000 miles they were completly shot. Tread bars showing and tread blocks pulling away from the carcass. I atrribute alot of this to improper air pressure. I ran the stated 55F and 80R.

I had the same tires and pressure new from the dealer. after a few thousand miles I could see the thread wearing down rapidly.


I lowered the pressure of the rear based on the manufacturer load charts and some of the posts here.


@ 7K I rotated the tires. The front tires, now on the rear have 14 K miles (7K miles on the rear) and there is no noticable wear. And the original rears that are now on the front are showing no additional wear.


I think I have the pressures right now for the type of loads I am carrying.Edited by: JohnnyO
 

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Great Post - here is some additional info.


My 2004 2500HD has a GVW of 9200# with a front axle rating of 4670# and a rear axle rating of 6084#. When I found the Michelin and Goodyear load ratings for the LT245/75/R16/E I discovered that the GM RECOMMENDED tire pressures of 55# front and 80# rear equaled the MAXIMUM axle rating. 55# of tire pressure equaled 2335# load X 2 (two tires on the front) equals 4670# the front axle rating (Same for the rear). So as stated before the recommended tire pressures of 55# front and 80# rear are for a truck that is MAXED out.


Last Saturday I weighed my truck at a public scales. 2004 2500HD, Ext Cab, Short Bed, LT, 8.1/Alli, 4X4, with a Century High C Cap, Rhino linning, 3/4 tank of gas, one person and no crap in the back.


Total 6760#, Front 3880#, Rear 2860#


When you compare those actual weights to the tire/load tables for the 245s it appears you could safely run 45# in the front and less than 35# in the rear.


Can't bring myself to run 35# in the rear so I settled on 50# all the way around for now. Truck rides and handles very well. May try 45# all the way around but I don't think I will feel any difference. Tire wear won't be an issure until the snow melts. Anyone running 45# all the way around?? How do you like it??
 

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Well, correct me if my thinking is wrong here - but you are saying that 55 psi matches the maximum load rating for the tire on the front. I disagree. At 55 psi you should not load the tire more than the maximum rating because of it's LOW INFLATION. The tire is E rated. The tire by design can carry MORE than the 55 psi recommended weight load when fully inflated to 80 psi. When you inflate the front to more than 55 psi you are NOT exceeding the load rating but actually creating load carrying margin beyond the recommended vehical loading. AND you are reducing excessive wear on a tire with low inflation for purposes of ride softness at the sacrifice of tire wear.
Sorry, just a bit of a sore spot with me when the factory recommended inflation caused my fronts to be scalloped, cupped, out-of-round and eaten-up for no reason other than trying to make a 7,000 pound 3/4 ton truck feel like a mini-van to appease whiners. I also suspect that a lot of the steering wear issues in our trucks might originate with the UNDERINFLATED tires causing imbalance and excessive wear on components. Funny that my 2001 with 76,000 miles on properly inflated fronts not only gets over 50,000 miles in tire wear but has had NO steering slop or rattle!
 

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Idle_Chatter: Don't disagree with a thing you said. True - IF you inflate the tires to a pressure that is above the AXLE rating but within the max pressure of the tire you build in a loading margin. However, I have seen lots of tires worn in the middle from what appears to be over-inflation with respect to the weight on the tire. I am certainly no tire expert but I have had good luck with REDUCING tire pressures (within reasonable limits) to be more in line with the actual weight on the tire using the load /inflation tables.


If you are not going to use the load/inflation tables for a specific tire to determine the recommended tire pressure based on actual weight on the tire, then what good are they? You would just inflate the tire to the maximum pressure listed on the sidewall and call it good.


Most of the tires dealers I have talked to don't seem to know s**t about propoer inflation. We need a "REAL TIRE EXPERT" to helps us out. I think we are all looking for safe load carrying capacity, good handling, good ride and long tire life. The issue is how do we get all of these things???
 

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Idle_Chatter said:
Well, correct me if my thinking is wrong here - but you are saying that 55 psi matches the maximum load rating for the tire on the front. I disagree. At 55 psi you should not load the tire more than the maximum rating because of it's LOW INFLATION. The tire is E rated. The tire by design can carry MORE than the 55 psi recommended weight load when fully inflated to 80 psi. When you inflate the front to more than 55 psi you are NOT exceeding the load rating but actually creating load carrying margin beyond the recommended vehical loading. AND you are reducing excessive wear on a tire with low inflation for purposes of ride softness at the sacrifice of tire wear.
Sorry, just a bit of a sore spot with me when the factory recommended inflation caused my fronts to be scalloped, cupped, out-of-round and eaten-up for no reason other than trying to make a 7,000 pound 3/4 ton truck feel like a mini-van to appease whiners. I also suspect that a lot of the steering wear issues in our trucks might originate with the UNDERINFLATED tires causing imbalance and excessive wear on components. Funny that my 2001 with 76,000 miles on properly inflated fronts not only gets over 50,000 miles in tire wear but has had NO steering slop or rattle!

I totally agree with everything above. My 2500 Ext/SB corners and breaks MUCH better with more that 55psi in the front tires. Due to the weight of the Duramax/Allison combination, even at very high tire pressures (80 psi or less) the ride is still very nice. Its too much air in the back of an unloaded bed that causes the harsh ride.
 

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Shark Bait said:
If you are not going to use the load/inflation tables for a specific tire to determine the recommended tire pressure based on actual weight on the tire, then what good are they? You would just inflate the tire to the maximum pressure listed on the sidewall and call it good.

The best tire pressure is that which causes the most even pressure across the entire contact patch while at the same time allowing for the largest contact patch. This is usually measured with a tire pyrometer, or chalk or other marking compound for those who do not have a tire pyrometer.


Overinflation might allow for better gas milage, but will quickly show itself with a much higher temperature on the center tread versus the inner and outer edge tread. Lower tire pressure might allow for a larger contact patch on uneven surfaces due to the tire being more able to envelop the uneven surface, but this will also cause for quicker tire wear, and less support to the tire sidewall showing up as vague and delayed stearing. The pyrometer will show this as BOTH outer edges of the tread being hotter than the center tread. Low pressure will also casue the tire to overheat, and if left long enough at high enough speeds, the tire will fail (blowout).


A tire pyrometer will also show too much negative camber as all the tires heat on inside edge of the tread. Of course not enough negative camber will show as excessive heat in the outer edge tread.


Taking this topic further to where none of you will probably have any problems, you can also use a pyrometer to determine if the rubber compound it too hard or too soft for the given application. After the temperature is even across the entire contact patch, too cold or too hot of an average temperature will show that the rubber compound is out of range for the given driving style.


I could go into how tires show caster, toe, and shock issues, but I think that would get a little off topic.Edited by: Amric
 
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