Tire pressure Question?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

k2c1959 · 10-18-2007, 11:16 PM

i am going to throw this out over here since this is where the majority of my time and most people on these boards seem to hang. Gimme some feedback here if anyone has any ideas on this....
this may sound like a stupid question but hey, here goes anyway.
i have a 2004 GMC sierra z71 ext cab 1/2 ton,(My daily driver) recommended tire pressure says 45 psi in door tag. Today i bought a new set of pro comp at's and was watching the guys putting them on and they were inflating the tires to 80 psi!! that is the pressure recommendation on the tires (10 plys) E load rating. I argued the point with them about running 80 lbs in the tires and they said it was recommended and should be run at that!! am i just crazy here or should they be run at 80 lbs. truck feels like it is on roller skates...I'm thinking 80 may be great if towing or hauling a load, but that is overkill for highway driving. am i wrong here, does anyone know? im thinking they need to be dropped down to 45 as GM recommended, they are the stock size that came on truck, just a different brand. Let me have it.

KFreddy · 10-18-2007, 11:48 PM

Take a look at the side wall of your new tires. There will be two psi #s one will be for the recommended inflation pressure and one for maximum inflation pressure. Fill your tire's cold pressure between the two and you'll be golden...

**WorkinLonghorn** · 10-19-2007, 12:44 AM

I'd go with 45 unless you are putting a huge load in there. Maybe they got sued for underinflating some tires and a blow-out resulted. Now to cover their rears they just fill to the max.But "max" isn't safe either in an unloaded truck-the tire "footprint" will be too small for optimum traction (also will ride badly).

Longhorn Man · 10-19-2007, 04:58 AM

i always roll at max pressure if the tire is the right size for the rim. Get better MPG, and tire wear has never been an issue.

Blazer1970 · 10-19-2007, 06:50 AM

Those tires have a very high load rating for the weight rating of the truck. At 80 psi you will wear out the center of the tread very quickly. Also, the ride will be very harsh. I would always run the fronts at 45 psi. If the truck is run mostly unloaded I would run the rears at 40 psi or so. Only increase the pressure in the rear tires if you have a substantial load in the bed. The maximum pressure rating on the side of the tiire is intended for the maximum load rating of the tire. If you were to weigh the front and rear of the truck you should run the tires somwhere around the same percentage of maximum pressure as the percentage of maximum load that you are putting on them. The door sticker on that half ton truck probably calls for a tire with a "C" load rating.

**truckdude239** · 10-19-2007, 07:28 AM

65 psi unless hauling a load never seen no unnormal wear when i worked for sam's club tire and battery center

10-18-2007, 11:16 PM	#1
k2c1959 OLD FART(I GUESS) Join Date: Jul 2005 Location: catoosa, okla Posts: 58	Tire pressure Question?? i am going to throw this out over here since this is where the majority of my time and most people on these boards seem to hang. Gimme some feedback here if anyone has any ideas on this.... this may sound like a stupid question but hey, here goes anyway. i have a 2004 GMC sierra z71 ext cab 1/2 ton,(My daily driver) recommended tire pressure says 45 psi in door tag. Today i bought a new set of pro comp at's and was watching the guys putting them on and they were inflating the tires to 80 psi!! that is the pressure recommendation on the tires (10 plys) E load rating. I argued the point with them about running 80 lbs in the tires and they said it was recommended and should be run at that!! am i just crazy here or should they be run at 80 lbs. truck feels like it is on roller skates...I'm thinking 80 may be great if towing or hauling a load, but that is overkill for highway driving. am i wrong here, does anyone know? im thinking they need to be dropped down to 45 as GM recommended, they are the stock size that came on truck, just a different brand. Let me have it. __________________ 1967 Shorty Stepside 1967 Shorty Fleet 1967 3/4 Fleet LB 1972 LB Fleet ....RAP IS TO MUSIC WHAT ETCH A SKETCH IS TO ART....

10-18-2007, 11:48 PM	#2
KFreddy Active Member Join Date: Apr 2005 Location: Miami, Florida Posts: 286	Re: Tire pressure Question?? Take a look at the side wall of your new tires. There will be two psi #s one will be for the recommended inflation pressure and one for maximum inflation pressure. Fill your tire's cold pressure between the two and you'll be golden... __________________ "The Great State of Florida"

10-19-2007, 12:44 AM	#3
WorkinLonghorn Senior Member Join Date: Dec 2006 Location: Studio City, Calif. Posts: 2,861	Re: Tire pressure Question?? I'd go with 45 unless you are putting a huge load in there. Maybe they got sued for underinflating some tires and a blow-out resulted. Now to cover their rears they just fill to the max.But "max" isn't safe either in an unloaded truck-the tire "footprint" will be too small for optimum traction (also will ride badly). __________________ '69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, 2nd owner, Work-Truck supreme. Best $300 I ever spent.

10-19-2007, 04:58 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Tire pressure Question?? i always roll at max pressure if the tire is the right size for the rim. Get better MPG, and tire wear has never been an issue.

10-19-2007, 06:50 AM	#5
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	Re: Tire pressure Question?? Those tires have a very high load rating for the weight rating of the truck. At 80 psi you will wear out the center of the tread very quickly. Also, the ride will be very harsh. I would always run the fronts at 45 psi. If the truck is run mostly unloaded I would run the rears at 40 psi or so. Only increase the pressure in the rear tires if you have a substantial load in the bed. The maximum pressure rating on the side of the tiire is intended for the maximum load rating of the tire. If you were to weigh the front and rear of the truck you should run the tires somwhere around the same percentage of maximum pressure as the percentage of maximum load that you are putting on them. The door sticker on that half ton truck probably calls for a tire with a "C" load rating. __________________ Tim

10-19-2007, 07:28 AM	#6
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,233	Re: Tire pressure Question?? 65 psi unless hauling a load never seen no unnormal wear when i worked for sam's club tire and battery center __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube



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