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Discussion Starter #1
Anyone have access to the data book specs on General tires for tire pressure vs. weight loading? I have a new 2004 3500 4X4 which came with General "E" load rating tires. I have tried several times to get a source of these tables from the General website - they refer me back to the manufacturer's weight data plate. I keep telling them that applies to the fully loaded vehicle, not an unladen one, but they seem to refuse to want answer the question.


Michelin, Firestone, and most tire manufacturers publish these tables on their websites or make them readily available to their customers (which is where the GM engineers got the original information to put on the dataplate...). Running a heavily sprung truck on max tire pressures is nonsense and probably adds stess to the truck as a whole. Using the tire manufacturer's specs is the safest way to balance tire pressure against differing loads for the front and rear axles of the truck, but General has been less than helpful in this regard. Withholding this information is foolish since it encourages the customer to guess at a lower pressure which, if too low, will allow excessive sidewall flex, attendant heat build-up, and premature tire failure.


If someone has these tables (which obviously do exist), I would appreciate the source. Otherwise, I'm going to guess the front at about 55# and the rear duals at 50# (which is probably too much, but errs on the side of caution)...


Anyone else run into this with General tires on the 3500 series?
 

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My '01 has the Wrangler AT/S tires and my door plate says 65 front 70 rear. Tires say max psi 80 lbs. Running empty a lower tire pressure will just result in a better ride. Loaded it's a whole new ballgame. I run the 65 & 70 when I'm towing my 5er (9.5k lbs.), empty I run 60 all around. BTW, if you find those tables make sure you post'em. I'd like to see them myself.


JP
 

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Discussion Starter #3
Here's a link to Michelin's tables - just click on the load inflation tables to view for some of their popular truck tires http://www.michelintruck.com/michelintruck/productguide/newprod/new tires.jsp. It does look like we probably shouldn't be running what's on the placard unloaded (loaded, I agree with you completely - air 'em up...). I'll probably just experiment some, making sure the duals never come close to touching in the back... The front tires should always carry more unloaded since they have the weight of the engine over them (a guess would be 4100 to 4500# unloaded on the front axle). The rear...maybe another 3500-4000# unloaded. So...maybe 50-55 psi front and 45-50 psi rear... Above 60 mph, going towards 80 mph, looks like you would need to increase tire pressure from those initial pressures about 5-15% to take into account higher temps. A little enlightened help from General tires would have made all this easier... I'm just guessing when their engineers have these answers... Maybe your Wranglers are listed on the Goodyear website?
 

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Went through this nut roll after I got my new truck. I checked out the BFG, Michelin and Goodyear web sites. Sent an E-Mail to BFG and got a reply TELEPHONE CALL from a tech rep who really took an interest in what I was trying to do. She, yes she, was very knowledgable and agreed with matching the weight of the axle to the load table published by the tire manufactuers. She confirmed the numbers I was using. The best way would be to weigh EACH tire but that is not too easy for most of us to do.


I took my truck to the local dump (Landfill to be politically correct) early one morning and got the front, back and total weights.


2004 Chevy 2500HD, Ex Cab/SB, 8.1/Alli, Topper, Rhino, Driver, 3/4 tank gas. Total 6760, Front 3880, Rear 2860.


Inflation Tables for LT 245/75 R16 E


35# = 1706, 40# = 1865, 45# = 2030, 50# = 2205, 55# = 2335, 60# = 2480, 65# = 2623, 70# = 2765, 75# = 2900, 80# = 3042


What do I run with no load - Front = 50#, Rear = 45# . I took the weight vs. table and added about 5# front and 10# rear. Rides nice and handles well. Just need to make sure to air up the rears when towing or carring a load.


Using the tables you could go to 45# in the front and 35# in the rear - I just can bring myself to do this. Have not tried 40# in the rear but I think it would work.


IMHO running placard pressures, 55# Front and 80# rear, unloaded is insane. Is anyone running less than 45# in the rear unloaded???
 

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just replaced the OEM tires on our 3500 ... had 58,000+ on them and plenty of tread left, only changed them because we are getting ready to take an 8,000+ mile trip to the left coast and back ... didn't like having to mess with changing the pressures in the inside rear dually tires so ran the max door pressure in all tires at all times .... plan to do same with the new tires


Jim
 

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I run the suggested psi on my '02, 70 in the front, 65 on the rears and the spare gets 80. no problems yet.
 

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Discussion Starter #7
Thanks for the replies - I believe I'll start with the lower pressures noted above and experiment. I believe Shark Bait is close to those values on the info he received from BFG. And, I do agree with him on running max tire pressure without a load - folks, that's just too stiff. A load range "E" tire has a substantially stiffer sidewall anyway - it will limit sidewall flex considerably all by itself and no heat build-up should really happen unless you lower pressures dramatically below the lower values being discussed. By airing to max (without a load), you have guaranteed a loss of ride quality - you're riding on tires with little or no flex - bricks. There's just no need for it until you load the vehicle - then, by all means, air up to max to protect the tire from heat build-up by stiffening the sidewalls (less flex). No reason to pound yourself or the truck when unloaded, tho.'
 
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