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Thread: effects of wheel offset/back spacing and tire width on handling

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    VCVC Member jrinaman's Avatar
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    effects of wheel offset/back spacing and tire width on handling

    i believe our vans had zero offset, so 3 1/2" backspacing on a 7" rim. can anyone confirm? while I like the look of wider fronts and less backspacing, I am curious as to its effects on handling. comparing same diam. tires, what effect would wider tires have vs. narrow? probably more important is how would an extreme offset compare to stock? I currently have 225-70-14's on torque thrusts on all 4 corners. when I installed them several years ago, I immediately noticed the difference in backspacing. probably 1/2"-3/4" farther out. add to that, fronts was already 1/4" from disc brake conversion. haven't heard it discussed in the van world but quite often hear complaints from 4 wheelers about poor handling with wider tires/more offset. granted, their offsets are more extreme but +/- an inch on our vans might make a difference, am I overthinking this or does it warrant concern?
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

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    VCVC Member rarechev's Avatar
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    ask Mike he has 10" wide rims on the front of primer donah.
    1970,350, 700R4, power tilt steering, power brakes, power windows

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    VCVC Charter Member Vanner68's Avatar
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    In a nutshell, deep rims on the front will increase steering effort, the wheels will not 'return to center' as quickly or not at all, faster kingpin wear, and in some cases, wandering in the lane. I've found that an 8" zero offset wheel avoids most of these issues except increased steering effort.

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    VCVC Member jrinaman's Avatar
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    Quote Originally Posted by Vanner68 View Post
    In a nutshell, deep rims on the front will increase steering effort, the wheels will not 'return to center' as quickly or not at all, faster kingpin wear, and in some cases, wandering in the lane. I've found that an 8" zero offset wheel avoids most of these issues except increased steering effort.

    The price you pay to look cool.
    not returning to center is what got me looking at it. increasing castor helped, heavy on toe in helped but will only return partially from either left or right. as you are aware, I had HUGE steering issues. this is nothing compared to that, not even close. none the less, not centering and 'floating' (not sure I would call it wandering/maybe tramlining?) doesn't feel right. with all of the issues I had and all I have done, I am probably more aware of ANY steering issues, real or imagined. add to that, been in a low mileage newer vehicle all winter so even a 100% perfect '64 wouldn't meet my expectations. I still haven't gotten over my trip to the ohio nats! while maybe overkill, if too much backspacing "might" cause an issue, wheels are getting replaced.
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

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    VCVC Member jrinaman's Avatar
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    not sure where stock would fall, here are pics of mine. as you can see, it is enough to notice.Click image for larger version. 

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    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

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    VCVC Member jrinaman's Avatar
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    pulled a wheel and found 6.75 std. and "almost" assumed std. meant zero offset. it doesn't! the back side has a lip at the top while the front is flatter. depending on which surface, it is heavy 1/2" or right at 3/4". the rotor ads another heavy 1/4" so up to just over an inch but likely the 3/4"-7/8". Click image for larger version. 

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    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

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    VCVC Member jrinaman's Avatar
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    Quote Originally Posted by rarechev View Post
    ask Mike he has 10" wide rims on the front of primer donah.
    wide rubber and extreme offset. hopefully he drops in and ads his 2 cents.
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

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    VCVC Charter Member Vanner68's Avatar
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    If you think about it, the further the centerline of the wheel is from the centerline of the kingpin, the more leverage the wheel has. I had a 74 Chevelle with deep dish 8" Cragars on the front (2" backspacing) If you let go of the steering wheel in a turn, the car would continue turning, would not straighten out until you turned the wheel back to manual. It could not be flat towed, once you went around a corner you had to stop and manually set the wheels straight again.
    Gregg Groff


    There's no place like 127.0.0.1

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    1965 Chevy G10 panel- OHC Pontiac inline 6

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    Certifiable Vanatic Leroy Jackson's Avatar
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    Deep offset wheels that stick out will cause the van to jump and wander on the highway.

    The closer you can keep the wheel to the axle, the better it will handle and track predictable. You wa t the wheels to follow the arch of the spindle with as little movement along the arch ( fwd and backwards) as the wheel pivots.

    Camber adjustment are not easy and require the axle to be physically bent.

    Caster adjustment can be made with shims. The more caster, the better it will return to center on its own. To much caster and your turning radius will increase and steering response will be lazy. Too little caster, the wheels will dart and feel twitchy
    The Raped Ape
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    VCVC Member jrinaman's Avatar
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    Quote Originally Posted by Leroy Jackson View Post
    Deep offset wheels that stick out will cause the van to jump and wander on the highway.

    The closer you can keep the wheel to the axle, the better it will handle and track predictable. You wa t the wheels to follow the arch of the spindle with as little movement along the arch ( fwd and backwards) as the wheel pivots.

    Camber adjustment are not easy and require the axle to be physically bent.

    Caster adjustment can be made with shims. The more caster, the better it will return to center on its own. To much caster and your turning radius will increase and steering response will be lazy. Too little caster, the wheels will dart and feel twitchy
    caster is 8-9 degrees, not wanting to push that much more. at 5 degrees, it wouldn't re center at all. 7 degrees was better but kinda wanders at straight ahead, 9 somewhat recenters but 'lazy and wanders'. bending the axle to accommodate the offset would likely be more than new rims and surely more than the 40 year old ones are worth. best I can figure, I am at -14 to -17 mm offset. at $120.00 a rim, I can get -2 mm offset.
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

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