wheel backspacing - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*red70* · 02-24-2011, 11:54 PM

Hey guys I have a 70 swb with 5 lug but I dont know if the rear end is 67-70 or 71-72 but I was looking to buy a set of 20x8 and 20x10 intro pentias and was hoping someone could help me with the backspacing. I am going to order them tomorrow if all possible.

Thanks
Bryce

The Big Green · 02-25-2011, 09:13 AM

71-72 were 5 lug, pre 71 was 6 lug. What's your plans for the setup, just static drop or bags?
Posted via Mobile Device

**lolife99** · 02-25-2011, 09:51 AM

Measure your rearend housing and get back to us.
Don't get in a hurry to order wheels.
More suspension info about your truck will also help.

I highly recommend measuring for wheels yourself and not taking anyone elses word,... when it comes to several thousand dollar$ worth of wheels.

*red70* · 02-25-2011, 11:50 AM

I have a 3-5 drop from cop and don't plan to do bags. How do I need to measure the rear end do it from axle flange to axle flange? How do I measure for the wheels myself?
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ChevLoRay · 02-25-2011, 12:37 PM

My '69 has the original axle under it. The '60-69 axles are about an inch narrower than the '70-72's. My 15x10-inch Wheel Vintiques (on the rear) have a 5-inch back space. They sit right and fit good. I don't know if I have a pic that will show it, and the truck is seriously (!!!) disassembled, so new pics won't happen for a while. You can see that they didn't stick out even as far as to be flush with the outside of the fender....the way I intended for them to fit. Oh, it also has a 2.5/4.0 static drop from ECE.

**lolife99** · 02-25-2011, 12:53 PM

Quote:

Originally Posted by red70

I have a 3-5 drop from cop and don't plan to do bags. How do I need to measure the rear end do it from axle flange to axle flange? How do I measure for the wheels myself?
Posted via Mobile Device

You can measure your rearend housing from "wheel mounting surface" to "wheel mounting surface".
(face of the brake drum)

Here's a good tech article for measuring for wheels:
http://www.carcraft.com/techarticles...ent/index.html

Just remember,... those 20x10's are going to measure 11" wide.
So all the measurements on the rear of your truck will need to be for 11 inches.
(front 20x8's will be 9" wide)

Static drop measurements will also be different than for a bagged drop.
Bagged trucks need more outboard clearance, than static dropped trucks, to clear the fender lip when air'd out.

*red70* · 03-08-2011, 11:32 PM

Ok guys I just measured my deafens housing and it is 57 inches so im guessing that it is the 67-70 housing so im wandering if I need somewhere along the lines of 5" of backspacing for the rear wheels on a 20x10 wheel? Or would I need less backspacing?
Posted via Mobile Device

**lolife99** · 03-08-2011, 11:43 PM

57" from where to where?
Backing plate?
Front side of the brake drum?

If it's the backing plate to backing plate measurement,... that sounds like the wider 71-72 housing.

*red70* · 03-09-2011, 12:49 PM

the measurements were from backing plate to backing plate but my axles were originally 6 lug and someone drilled them out to be 5 lug

**lolife99** · 03-09-2011, 12:56 PM

Some 1970 rearends are what I call the "transition year" rearends.
They had the wider housing with 6-lug axles.
My 1970 stepside has this rearend.
My '69 swb truck has the narrower rearend.
(approx. 55-1/2" backing plate to backing plate)
With the wider housing I would use a 5.5" backspace, on a 20x10, (If you never plan on bagging it).
Up front I would use a 5.5" BS on a 20x8.5 wheel.
I like the wheels under the fender.

*Fitz* · 03-09-2011, 01:00 PM

I'm running 17x8's on front with a 4.5 in backspace and 17x10's rear with 5 in backspace on my 67 stepside.

*red70* · 03-09-2011, 09:34 PM

My front suspension consists of 71-72 disc brakes would i still be ok running 5.5 backspace in the front? Ive heard that the factory disc set up pushes the wheels out a little when you run that set up?

**lolife99** · 03-09-2011, 10:26 PM

Quote:

Originally Posted by red70

My front suspension consists of 71-72 disc brakes would i still be ok running 5.5 backspace in the front? Ive heard that the factory disc set up pushes the wheels out a little when you run that set up?

Yes.
This is member 72BlckButy's truck.
20x8.5 (5.5" BS) up front.
Perfect for a static dropped truck, in my opinion.

**lolife99** · 03-09-2011, 10:29 PM

I'm pretty sure the Intros will come in a 20x8.5 only. (not 20x8.5)
If they actually are a 20x8 the backspace will need to be 5".

02-24-2011, 11:54 PM	#1
red70 Account Suspended Join Date: Sep 2006 Location: Kingston, TN Posts: 178	wheel backspacing Hey guys I have a 70 swb with 5 lug but I dont know if the rear end is 67-70 or 71-72 but I was looking to buy a set of 20x8 and 20x10 intro pentias and was hoping someone could help me with the backspacing. I am going to order them tomorrow if all possible. Thanks Bryce

02-25-2011, 09:13 AM	#2
The Big Green Registered User Join Date: Oct 2007 Location: Fort Smith,AR Posts: 1,304	Re: wheel backspacing 71-72 were 5 lug, pre 71 was 6 lug. What's your plans for the setup, just static drop or bags? Posted via Mobile Device

02-25-2011, 09:51 AM	#3
lolife99 67-72 parts collector,… Join Date: Nov 2002 Location: Mid-MO Posts: 22,701	Re: wheel backspacing Measure your rearend housing and get back to us. Don't get in a hurry to order wheels. More suspension info about your truck will also help. I highly recommend measuring for wheels yourself and not taking anyone elses word,... when it comes to several thousand dollar$ worth of wheels. __________________ Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823

02-25-2011, 11:50 AM	#4
red70 Account Suspended Join Date: Sep 2006 Location: Kingston, TN Posts: 178	Re: wheel backspacing I have a 3-5 drop from cop and don't plan to do bags. How do I need to measure the rear end do it from axle flange to axle flange? How do I measure for the wheels myself? Posted via Mobile Device

02-25-2011, 12:37 PM	#5
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: wheel backspacing My '69 has the original axle under it. The '60-69 axles are about an inch narrower than the '70-72's. My 15x10-inch Wheel Vintiques (on the rear) have a 5-inch back space. They sit right and fit good. I don't know if I have a pic that will show it, and the truck is seriously (!!!) disassembled, so new pics won't happen for a while. You can see that they didn't stick out even as far as to be flush with the outside of the fender....the way I intended for them to fit. Oh, it also has a 2.5/4.0 static drop from ECE. Attached Images __________________ 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. Last edited by ChevLoRay; 02-25-2011 at 12:39 PM.

03-08-2011, 11:32 PM	#7
red70 Account Suspended Join Date: Sep 2006 Location: Kingston, TN Posts: 178	Re: wheel backspacing Ok guys I just measured my deafens housing and it is 57 inches so im guessing that it is the 67-70 housing so im wandering if I need somewhere along the lines of 5" of backspacing for the rear wheels on a 20x10 wheel? Or would I need less backspacing? Posted via Mobile Device

03-08-2011, 11:43 PM	#8
lolife99 67-72 parts collector,… Join Date: Nov 2002 Location: Mid-MO Posts: 22,701	Re: wheel backspacing 57" from where to where? Backing plate? Front side of the brake drum? If it's the backing plate to backing plate measurement,... that sounds like the wider 71-72 housing. __________________ Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823 Last edited by lolife99; 03-08-2011 at 11:43 PM.

03-09-2011, 12:49 PM	#9
red70 Account Suspended Join Date: Sep 2006 Location: Kingston, TN Posts: 178	Re: wheel backspacing the measurements were from backing plate to backing plate but my axles were originally 6 lug and someone drilled them out to be 5 lug

03-09-2011, 12:56 PM	#10
lolife99 67-72 parts collector,… Join Date: Nov 2002 Location: Mid-MO Posts: 22,701	Re: wheel backspacing Some 1970 rearends are what I call the "transition year" rearends. They had the wider housing with 6-lug axles. My 1970 stepside has this rearend. My '69 swb truck has the narrower rearend. (approx. 55-1/2" backing plate to backing plate) With the wider housing I would use a 5.5" backspace, on a 20x10, (If you never plan on bagging it). Up front I would use a 5.5" BS on a 20x8.5 wheel. I like the wheels under the fender. __________________ Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823 Last edited by lolife99; 03-09-2011 at 12:56 PM.

03-09-2011, 01:00 PM	#11
Fitz Account Suspended Join Date: Jan 2007 Location: Tucson Posts: 2,183	Re: wheel backspacing I'm running 17x8's on front with a 4.5 in backspace and 17x10's rear with 5 in backspace on my 67 stepside.

03-09-2011, 09:34 PM	#12
red70 Account Suspended Join Date: Sep 2006 Location: Kingston, TN Posts: 178	Re: wheel backspacing My front suspension consists of 71-72 disc brakes would i still be ok running 5.5 backspace in the front? Ive heard that the factory disc set up pushes the wheels out a little when you run that set up?

03-09-2011, 10:29 PM	#14
lolife99 67-72 parts collector,… Join Date: Nov 2002 Location: Mid-MO Posts: 22,701	Re: wheel backspacing I'm pretty sure the Intros will come in a 20x8.5 only. (not 20x8.5) If they actually are a 20x8 the backspace will need to be 5". __________________ Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823



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