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#1 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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8 lug inflation pressures when not towing or hauling
What should I run for pressure in my tires (LT style) for pressure when just driving around with no load?
The tires have a max capacity at 65psi, since they're a truck tire, but that's a lot of pressure and makes for a pretty harsh rish (am I really thinking about ride quality in one of these? I guess so!). Is it safe to run 40? While I'm at it, the shop manual does not list (or I could not find) lug nut torque values. Where are they found (and what do they say)? Maybe these are so basic they're in the owner's manual and not the shop manual, but I couldn't find either.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#2 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,647
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Re: 8 lug inflation pressures when not towing or hauling
40 is fine, you might also try 35. Do a chalk test initially, then monitor tread depth regularly. Tread depth gauges are cheap and you'll find wear patterns long before your eyes can detect them.
I'll be honest, I always torque the lugs on my other vehicles but never on my K20. I just cross-tighten them by hand until they are TIGHT. No problems in 39 years, knock wood...
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#3 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,553
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Re: 8 lug inflation pressures when not towing or hauling
I run mine at 50psi and torque to 110lbs
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#4 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
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Re: 8 lug inflation pressures when not towing or hauling
Thanks! What's the chalk test? Draw a line across the tread and see what wears off first?
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#5 |
Registered User
Join Date: Dec 2012
Location: kearney nebraska
Posts: 613
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Re: 8 lug inflation pressures when not towing or hauling
40 psi is a good pressure to run. The heavier tire needs more air to wear properly. 40/50 is what I run in my 10 ply tires empty.
As for wheel torque, I torque mine to 140. That is what all newer 7/8 lug gm vehicle torque spec is.
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1972 GMC C20 Custom Camper 350/TH350 |
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#6 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,647
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Re: 8 lug inflation pressures when not towing or hauling
Yup. A lot of guys swear by it to at least establish a baseline pressure.
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#7 |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,721
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Re: 8 lug inflation pressures when not towing or hauling
Bigger the tire, less pressure needed for the same load. I run the 8 lug 35 12.5 16.5 D series tires on my Jimmy at 24 psi for road work. The Mickey Thompsons that used to be on there I ran at 22.
I think I ran the 265 75 16 D rated tires on my old C2500 GMC at 40 psi unless I was hauling so good advice from the previous posters.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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#8 |
The Niner
![]() Join Date: Nov 2010
Location: Broad Brook, CT
Posts: 2,494
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Re: 8 lug inflation pressures when not towing or hauling
I run 45-50 all the way around.
With Michelins and a coil spring rear my truck rides very well for a 3/4 ton pickup.
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"A good racer is one whose head is in communication with his balls." - Richie Evans 1970 C/20 - 402/TH400/3.54s - 74K miles 2003 GMC Sierra 2500 - Wheatland Yellow Niner Progression Thread: http://67-72chevytrucks.com/vboard/s...d.php?t=697183 Classic Trucks article: https://www.motortrend.com/features/...et-c20-driven/ |
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#9 |
Registered User
![]() Join Date: Mar 2005
Location: Jurupa Valley, Ca
Posts: 1,210
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Re: 8 lug inflation pressures when not towing or hauling
I typically run ath about 45 PSI and about the torque for the lug nuts I copied this from the Chevrolet truck service manual:
WHEEL NUT TORQUES- 10-30 Series On a new vehicle or after the wheel has been changed, the wheel nut torque must be checked at 100, 1,000 and 6,000 m iles and every 6,000 m iles thereafter. Retorque wheel nuts to 55-65 ft. lbs. on 10 Series and 65 to 90 ft. lbs. for 20-30 Series models. Heavy Duty Wheels on 30 Series On a new vehicle or after the wheel has been changed, the wheel nut torque must be checked at 100, 500, and 1.000 m iles and every 1,000 m iles thereafter. Torque wheel nuts 200-250 lbs. ft. on 30 Series trucks with 11,000 lb. rear axles, RPO H-22.
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Terry 1970 Custom Camper/C20 , GM Crate 350/7004R, Dana 60, factory AC |
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