Torque and PSI for non standard wheels and tires?

Discussion in 'The Hides' started by Electra Bob, Jun 3, 2020.

  1. Electra Bob

    Electra Bob Well-Known Member

    So I've basically been running around with a best guess on both of these settings and have always been meaning to get some input on what everyone else does, or considers appropriate.

    I got no response at all when I posed the question to both the tire and wheel manufacturer. I'm guessing it's a liability thing.

    So what would you run for wheel nut torque and tire pressure for a 235/55R18 104V tire on an
    American Racing VN215 Classic Torq Thrust II wheel on a 1972 Electra?

    If it makes a difference, original drums and studs in the rear, new Baer rotor/studs in front.

    Cheers
    Bob
     
  2. BUICKRAT

    BUICKRAT Got any treats?

    100 lbs/ft should do it.
     
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Is that a steel or aluminum wheel? 100 ft. lbs is for the stock steel wheel. I would go 80 on an aluminum wheel.

    Look at your tires and tell me what the maximum inflation pressure is on those tires. It will be on the sidewall. Run 85-90% of that. Adjust for ride comfort.
     
  4. Electra Bob

    Electra Bob Well-Known Member

    Thanks Larry,

    Well I've been using 80 ft lbs and they are aluminum wheels so I got that right.

    Tires say:
    max load and pressure.jpg
    Which would make your recommendation 42-45 psi and purely based on what my Silverado asked for, with a similar size and vehicle load, I have been using 36 psi.

    After ~ 5,000 miles the tires are not showing any abnormal wear but I'll try bumping it up to 42 psi and see how it feels.

    Cheers!
    Bob
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    That's what I am talking about. No one looks at tire sidewalls anymore. Inflation pressures have gone up. Maximum inflation pressures for the Bias Ply tires that came on our cars was 32 psi. Radials commonly listed 35 psi. Now, 44 and 51 psi are common to see. In general, 85-90% of the max provides the best compromise in handling/ride, and wear. I have Coopers on both my GS and 98 Riviera. They both list a max inflation of 44 psi. Through trial and error, I have determined that 37 psi works best in my GS. The Riviera has 40 psi all around. Both cars ride really nice with those pressures. My Riviera came with 35 psi tires from the factory. Tire placard says 30 all around. If I run that, the car wallows in the corners, handling is sloppy and not as precise. Same for the GS. When I first bought the Coopers for the GS, I ran 30 psi. I could hear the tires squealing when I turned in parking lots. Handling was sloppy. I tried 40, but the ride was hard. I settled for 37-38 which worked best. like I said, 85-90% usually works best.
     
  6. CJay

    CJay Supercar owner Staff Member

    Not to disagree with Larry, but the factory torque rating is 75 ft lbs on a 1/2" stud. Buick calls for 70 ft/ lbs on a 7/16" stud. The factory inflation pressure on fiberglass beltd tire is 26 psi

    Larry, do you have a service manual? :p
     
  7. CJay

    CJay Supercar owner Staff Member

    And I put 35 or 40 lbs in my tires, the car rides like a pogo stick. Even the Challenger gets 32
     
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I do, you are right, 70 ft. lbs in my 70 Manual. My 98 Riviera gets 100 ft. lbs. I got confused. :)

    Both my cars ride great. Take you for a ride some time. Maybe you should look at the sidewalls. You have Bias Plys on some of your cars. No one suggests higher pressures with those. Next time you see John Csordas, ask him what inflation pressures he uses with today's tires.
     
  9. Electra Bob

    Electra Bob Well-Known Member

    Should have asked this question a *long* time ago!

    Set the cold pressure up from my usual 36 to 42 psi and what a difference!

    The car had always tended to wander a bit and that has almost all but disappeared. Paradoxically the ride with the increased pressure has improved!

    Larry - I owe you a cold one!

    Cheers
    Bob
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Not surprised Bob. Even tire manufacturers get it wrong. They tell you to follow the tire placard or owners manual. That information is outdated. I would follow new car tire info, but anything more than 5-10 years old may no longer apply to today's new tires. I'm surprised Jason's Challenger only takes 32 psi.
     
  11. Houmark

    Houmark Well-Known Member

    Just to chime in, I have 235/40-19 up front, and 275/35-19 rear.. Modern tires, on alloy rims, with adapters (5x5" to 5x114,3) and I have 42psi/3bar in all tires, and all nuts and bolts are torqued with 130nm/95ft-lb with zink/kobber grease applied ;) It's on a 65 Electra, and been there for years without uneven wear etc..
     

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