I'm looking at some wheels and I need help with the offset. Will they fit? And please explain what it will be compared to factory.
18X8.5 56mm offset
18X10.5 56mm offset
Offset help please
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Re: Offset help please
Gene Beaird,
Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2018 Tahoe PPV (her car)
1995 DGGM Impala SS
1985 Firebird - 310 LS1 C Prepared autocross car.
1980 Bluebird Wanderlodge
And some others
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Pearland, Texas
2012 Caprice 9C1
1992 B4C 1LE Camaro
2018 Tahoe PPV (her car)
1995 DGGM Impala SS
1985 Firebird - 310 LS1 C Prepared autocross car.
1980 Bluebird Wanderlodge
And some others
Do YOU have my SPID?
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Re: Offset help please
Some perspective - Chevy SS sedan wheel offsets, which we KNOW will fit a PPV:
Front - 8.5" +48mm (stock tire 245/40-19)
Rear - 9.0" +57mm (stock tire 275/35-19)
Your front 8.5" +56 will be too far inward - the tire will probably rub against the strut - an appropriate size would be 245/45-18 or 255/45-18
The rear 10.5" +56 will be "close" but may work, although there may be contact between outer edge of tire and body opening
A 10.5" wheel will require a tire of at least 275/40 section width/aspect ratio for proper sidewall fitment
https://www.willtheyfit.com/" onclick="window.open(this.href);return false;
Calculations: other sizes can be plugged in to the calculator to check fitment
Front: compares 245/40-19 & 245/45-18
- https://www.willtheyfit.com/index.php?w ... offset2=56" onclick="window.open(this.href);return false;
Rear: notice how sidewall stretch changes with the wider wheel - compares 275/35-19 & 275/40-18, and 295/35-18 (may be too short)
- https://www.willtheyfit.com/index.php?w ... offset2=56" onclick="window.open(this.href);return false;
- https://www.willtheyfit.com/index.php?w ... offset2=56" onclick="window.open(this.href);return false;
Front - 8.5" +48mm (stock tire 245/40-19)
Rear - 9.0" +57mm (stock tire 275/35-19)
Your front 8.5" +56 will be too far inward - the tire will probably rub against the strut - an appropriate size would be 245/45-18 or 255/45-18
The rear 10.5" +56 will be "close" but may work, although there may be contact between outer edge of tire and body opening
A 10.5" wheel will require a tire of at least 275/40 section width/aspect ratio for proper sidewall fitment
https://www.willtheyfit.com/" onclick="window.open(this.href);return false;
Calculations: other sizes can be plugged in to the calculator to check fitment
Front: compares 245/40-19 & 245/45-18
- https://www.willtheyfit.com/index.php?w ... offset2=56" onclick="window.open(this.href);return false;
Rear: notice how sidewall stretch changes with the wider wheel - compares 275/35-19 & 275/40-18, and 295/35-18 (may be too short)
- https://www.willtheyfit.com/index.php?w ... offset2=56" onclick="window.open(this.href);return false;
- https://www.willtheyfit.com/index.php?w ... offset2=56" onclick="window.open(this.href);return false;
Bill Harper
inov8r@windstream.net
inov8r@windstream.net
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Re: Offset help please
Thanks Bill, that link helped understand better.
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Re: Offset help please
I'm guessing that wheels with those offsets are most likely from Corvette, which are 120.65mm, or 4.75" bolt circle, with a larger wheel center bore (70.3mm vs 67.1mm) than used on Zeta/PPV.
If that is the case, just be aware that the wheel stud pattern is not the same on PPV (120mm, or 4.72" bolt circle), and you'll want to run a hub-centric ring setup to properly support them, and either have the wheels machined to correct the lug nut seat alignment, or use floating-seat lug nuts (yes they do exist) to avoid side-loading of wheel studs and provide full-contact support of the wheels at the lug seat tapers.
This is a contentious issue that many choose to ignore and disagree with - I'm only stating this to provide full understanding of the difference. There's no doubt that many run wheels that don't match the OE specs and report no problems.
If that is the case, just be aware that the wheel stud pattern is not the same on PPV (120mm, or 4.72" bolt circle), and you'll want to run a hub-centric ring setup to properly support them, and either have the wheels machined to correct the lug nut seat alignment, or use floating-seat lug nuts (yes they do exist) to avoid side-loading of wheel studs and provide full-contact support of the wheels at the lug seat tapers.
This is a contentious issue that many choose to ignore and disagree with - I'm only stating this to provide full understanding of the difference. There's no doubt that many run wheels that don't match the OE specs and report no problems.
Bill Harper
inov8r@windstream.net
inov8r@windstream.net
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Re: Offset help please
Thanks Bill, I think the back wheel will be pushing it. What do you think about using the front wheels all the way around?
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Re: Offset help please
Unless a spacer is used to push the wheel out to a position that ensures no tire/wheel contact with the strut, the problem will be that the +56 offset on an 8.5" wheel will give the car a sunken look--the wheels will appear to be deep(er) into the wheel openings, than even stock wheels.
Put another way - imagine the SS sedan rear wheel (+57mm) with another 1/4" to 1/2" of rim width removed (from 9" to 8.5") from the outboard side of the wheel. Same in front--SS wheel is 8.5 +48mm, and you put that +56 wheel in it's place, it's now 8mm further inboard, and would end up looking "lost" in stock wheel openings--and, as mentioned above, may not clear the strut.
Put another way - imagine the SS sedan rear wheel (+57mm) with another 1/4" to 1/2" of rim width removed (from 9" to 8.5") from the outboard side of the wheel. Same in front--SS wheel is 8.5 +48mm, and you put that +56 wheel in it's place, it's now 8mm further inboard, and would end up looking "lost" in stock wheel openings--and, as mentioned above, may not clear the strut.
Bill Harper
inov8r@windstream.net
inov8r@windstream.net
Re: Offset help please
Hey Bill, I know that was two years ago but I'm in the middle of attempting to widen my rear steelies to about 10" or from what you mentioned about a 10-1/2" but may not be doable with our OEM offset. But just to check my math, if he's using a 10-1/2" wide wheel at positive 56 offset does that leave about 7.455 backspace as in my sketch?
BTW what is our OEM offset?
Thanks
Walt
BTW what is our OEM offset?
Thanks
Walt
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Walt (AKA:Capeasy) So. Cal.
2013 Caprice 9C1,Huron white, Blackbear tune, DOD Delete, Texas Speed stage 2 cam with all the goodies, Circle D 258 mm converter, 3200 stall. Spectra CAI, 3.45 Diff, deep trans pan. BlackWidow Venom exhaust,Granatelli oval cutouts, Doug Thorley tri-Y headers, Pedders coilovers,Tower brace, Widend OE. rear wheels to 10" wide with 295 Nitto's
2013 Caprice 9C1,Huron white, Blackbear tune, DOD Delete, Texas Speed stage 2 cam with all the goodies, Circle D 258 mm converter, 3200 stall. Spectra CAI, 3.45 Diff, deep trans pan. BlackWidow Venom exhaust,Granatelli oval cutouts, Doug Thorley tri-Y headers, Pedders coilovers,Tower brace, Widend OE. rear wheels to 10" wide with 295 Nitto's