Wheel offset calculators & offset explained - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TennesseeZ · 07-04-2010, 09:11 PM

There have been several questions asked concerning ofset and swapping wheels lately so I thought I'd do a Google for some easy to understand info, here's some of what's out there:

Offset Calculator 1010Tires

Offset Calculator GTSparkplugs

Wheelsandtires.com

Tirerack.com Wheel Offset explained

TireRack Wheel Tech Articles

ChevLoRay · 07-04-2010, 11:25 PM

Thanks for putting this info together for us all.

Gordonr1973 · 07-12-2010, 10:32 PM

Wheel Backspacing and Offset

Before mounting a set of aftermarket wheels, there are some dynamics involved with fitment that are best to understand first.
1. Wheel Diameter. This is the diameter of the wheel. Stock wheels are commonly 15 or 16 inch diameter. This dimension is usually in 1 increments (i.e. 15, 16, 17) but some manufacturers offer 16.5, which is rare.
2. Wheel Width. This is the width of the wheel, measured inside the outer lip of the wheel. This dimension is usually in 1/2 increments (i.e. 7.5, 8)
3. Wheel Center. This is the center of the wheel in relation to the width.
4. Offset. The distance from the centerline of the wheel to the face of the mounting surface of the wheel that contacts the hub.
4.1 Zero Offset. Indicates the mounting surface is at the wheel center.
4.2. Negative Offset. Indicates the mounting surface is behind (or inboard) the centerline of the rim. This is often found on standard rear-wheel-drive vehicles and on so-called reversed rims. (Diagram below shows negative offset)
4.3 Positive Offset. Indicates the mounting surface is in front of (or outboard) the centerline of the rim. This is often found on front-wheel-drive vehicles. Stock Tacoma wheels have Positive offset.
5. Backspacing. The distance from the mounting surface to the inside lip of the wheel. This measurement is closely related to offset (without actually measuring, backspacing is about equal to [Wheel Width / 2] + [Offset] + [about 1/4] ).
6. Centerbore. The centerbore of a wheel is the size of the machined hole on the back of the wheel that centers the wheel properly on the hub of the car. This hole is machined to exactly match the hub so the wheels are precisely positioned, minimizing the chance of a vibration. This measurement may be critical to clear the hubs of a 4WD.
7. Bolt Circle. Also known as PCD (Pattern Circle Diameter). The bolt circle represents the diameter of an imaginary circle that goes through the center of the bolt holes. 4x2 Tacoma Bolt Circle: 5 lug on 4.5 PCD; 4x4/Prerunner Tacoma Bolt Circle: 6 lug on 5.5 PCD.

SRVBLUES64 · 01-20-2011, 07:04 PM

more confused im thinking on putting a 17x9 in the rear of my 66 c10 can some one help me with just giving me the correct backspacing 17x8 up front

72BlckButy · 01-20-2011, 07:18 PM

SRVBLUES64 - there's a lot more at stake than just offering BS numbers. We need some additional info:

Are you running drums or disc brakes?
Are you running drop spindles?
How much drop?
Static/Bag drop?
What size tires are you wanting to run?
Did you swap in a late model crossmember?
Etc.

SRVBLUES64 · 01-20-2011, 07:54 PM

more info Im putting 2.5 drop spindles and 5 lug disc conversion up front with drum set up in the back with new axles fro 5 lug and I think a 4 inch drop, as for wheels 17x8 with 255x60x17 front and for the back 17x9.5 with 275x60x17 it should have a rake with a hot rod stance. I took a pic of the rear end I do not know the size or lenght I hope thats what your asking I will check in the morning I hope that helps Thanks Jeff

72BlckButy · 01-20-2011, 08:26 PM

What width is the rearend?

Kim57 · 01-21-2011, 01:10 AM

Quote:

Originally Posted by SRVBLUES64

more confused im thinking on putting a 17x9 in the rear of my 66 c10 can some one help me with just giving me the correct backspacing 17x8 up front

If you go here it shows how to measure so you can figure out the backspacing. Hope it helps.
Kim
http://www.stocktonwheel.com/wheel_guide.php

**N2TRUX** · 01-22-2011, 03:56 PM

This is now in the FAQ forum- LINK

07-04-2010, 09:11 PM	#1
TennesseeZ Countdown Survivor Join Date: Aug 2007 Location: Bean Station, East Tennessee Posts: 9,676	Wheel offset calculators & offset explained There have been several questions asked concerning ofset and swapping wheels lately so I thought I'd do a Google for some easy to understand info, here's some of what's out there: Offset Calculator 1010Tires Offset Calculator GTSparkplugs Wheelsandtires.com Tirerack.com Wheel Offset explained TireRack Wheel Tech Articles __________________ 93 Yukon 89 Silverado Z71 SWB Sport 91 K 2500 Silverado "Lobuk-Worktruk" A MAN OF HONOR DOES NOT LIE, CHEAT, OR STEAL, NOR TOLERATE THOSE WHO DO. Gettin' old ain't for sissies.

07-04-2010, 11:25 PM	#2
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: Wheel offset calculators & offset explained Thanks for putting this info together for us all. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

07-12-2010, 10:32 PM	#3
Gordonr1973 Home Built '87 Join Date: May 2010 Location: Calgary, Alberta Canada Posts: 1,829	Re: Wheel offset calculators & offset explained Wheel Backspacing and Offset Before mounting a set of aftermarket wheels, there are some dynamics involved with fitment that are best to understand first. 1. Wheel Diameter. This is the diameter of the wheel. Stock wheels are commonly 15 or 16 inch diameter. This dimension is usually in 1 increments (i.e. 15, 16, 17) but some manufacturers offer 16.5, which is rare. 2. Wheel Width. This is the width of the wheel, measured inside the outer lip of the wheel. This dimension is usually in 1/2 increments (i.e. 7.5, 8) 3. Wheel Center. This is the center of the wheel in relation to the width. 4. Offset. The distance from the centerline of the wheel to the face of the mounting surface of the wheel that contacts the hub. 4.1 Zero Offset. Indicates the mounting surface is at the wheel center. 4.2. Negative Offset. Indicates the mounting surface is behind (or inboard) the centerline of the rim. This is often found on standard rear-wheel-drive vehicles and on so-called reversed rims. (Diagram below shows negative offset) 4.3 Positive Offset. Indicates the mounting surface is in front of (or outboard) the centerline of the rim. This is often found on front-wheel-drive vehicles. Stock Tacoma wheels have Positive offset. 5. Backspacing. The distance from the mounting surface to the inside lip of the wheel. This measurement is closely related to offset (without actually measuring, backspacing is about equal to [Wheel Width / 2] + [Offset] + [about 1/4] ). 6. Centerbore. The centerbore of a wheel is the size of the machined hole on the back of the wheel that centers the wheel properly on the hub of the car. This hole is machined to exactly match the hub so the wheels are precisely positioned, minimizing the chance of a vibration. This measurement may be critical to clear the hubs of a 4WD. 7. Bolt Circle. Also known as PCD (Pattern Circle Diameter). The bolt circle represents the diameter of an imaginary circle that goes through the center of the bolt holes. 4x2 Tacoma Bolt Circle: 5 lug on 4.5 PCD; 4x4/Prerunner Tacoma Bolt Circle: 6 lug on 5.5 PCD. Attached Images __________________ Gordon 1998 White Chev ext cab 2WD (Summer Project) http://67-72chevytrucks.com/vboard/s...d.php?t=408424 1987 Chev Silverado SWB (Winter Project Rebuild) http://67-72chevytrucks.com/vboard/s...d.php?t=424833 Truck Club http://67-72chevytrucks.com/vboard/s...d.php?t=466969

01-20-2011, 07:04 PM	#4
SRVBLUES64 Registered User Join Date: Nov 2009 Location: Noblesville, Indiana Posts: 430	Re: Wheel offset calculators & offset explained more confused im thinking on putting a 17x9 in the rear of my 66 c10 can some one help me with just giving me the correct backspacing 17x8 up front

01-20-2011, 07:18 PM	#5
72BlckButy Tot Roddin' Join Date: Apr 2005 Location: Mid-MO Posts: 24,461	Re: Wheel offset calculators & offset explained SRVBLUES64 - there's a lot more at stake than just offering BS numbers. We need some additional info: Are you running drums or disc brakes? Are you running drop spindles? How much drop? Static/Bag drop? What size tires are you wanting to run? Did you swap in a late model crossmember? Etc. __________________ -Nate 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package)

01-20-2011, 07:54 PM	#6
SRVBLUES64 Registered User Join Date: Nov 2009 Location: Noblesville, Indiana Posts: 430	Re: Wheel offset calculators & offset explained more info Im putting 2.5 drop spindles and 5 lug disc conversion up front with drum set up in the back with new axles fro 5 lug and I think a 4 inch drop, as for wheels 17x8 with 255x60x17 front and for the back 17x9.5 with 275x60x17 it should have a rake with a hot rod stance. I took a pic of the rear end I do not know the size or lenght I hope thats what your asking I will check in the morning I hope that helps Thanks Jeff Attached Images Last edited by SRVBLUES64; 01-20-2011 at 09:36 PM. Reason: more info

01-20-2011, 08:26 PM	#7
72BlckButy Tot Roddin' Join Date: Apr 2005 Location: Mid-MO Posts: 24,461	Re: Wheel offset calculators & offset explained What width is the rearend? __________________ -Nate 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package)

01-22-2011, 03:56 PM	#9
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,023	Re: Wheel offset calculators & offset explained This is now in the FAQ forum- LINK __________________ Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra"



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