8 lug stud spacing - The 1947 - Present Chevrolet & GMC Truck Message Board Network

fun in dirt · 08-05-2009, 10:40 AM

I found this killer dealer on a set of wheels http://northmiss.craigslist.org/pts/1305110606.html , but don't the 8 lugs for '99 F250 use that 170?mm stud spacing instead of 6.5"? I really wish they would fit...is there any way it could work?

ghettoluxury · 08-05-2009, 10:59 AM

Correct they are 170mm. The only way it will work is with adapters

**Dieselwrencher** · 08-05-2009, 08:22 PM

I saw one time where a guy that had a sweet 91 F-350 had 02 super duty 8 lug alloy wheels on it. The guy owned a machine shop and machined the wheels and added an offset slug that he also machined and was able to bolt the wheels to his standard truck. It seems like a lot of work though.

MickMc · 08-11-2009, 12:47 PM

It seems to me that 6.5 inch bolt diameter pattern is 165.1mm
And 170mm is 6.69 inch
Therefore the difference in diameter is only .095 inch

10 thousandths is not very much

If my math is correct

The more important question will be if the backspacing is correct.
The high offset wheels have a problem clearing early tie rods and brakes and...

Just my two cents

Mick

**Dieselwrencher** · 08-11-2009, 05:42 PM

Good input Mick.

LONGHAIR · 08-11-2009, 07:07 PM

Quote:

Originally Posted by MickMc

It seems to me that 6.5 inch bolt diameter pattern is 165.1mm
And 170mm is 6.69 inch
Therefore the difference in diameter is only .095 inch

10 thousandths is not very much

If my math is correct

Just my two cents

Mick

Your metric conversion math is absolutely correct...but the difference is more than you are thinking.
5 millimeters is essentually 3/16"
The difference (english) between 6.5 and 6.69.....is .190 (not .095)
.190 is close enough to 3/16" (.187)
So, what it all comes down to is....does 3/16 matter? IMHO, yes. The wheel "might" physically fit over the lug studs, but the nuts will never tighten properly. They will bind on the edges of the taper before seating. THis will stress the studs.

Of course all of this is moot if the off-set doesn't "work"

Blazer1970 · 08-11-2009, 07:18 PM

If you tried to run those Ford wheels on an 8 on 6 1/2" hub, the lug nuts would come loose on one side of the truck very quickly.

ghettoluxury · 08-11-2009, 07:20 PM

I once had a set of 170 mm rims on a 6.5in 8lug chevy (because I was told they were 6.5in) and it had a wicked hop going down the road. So your answer is yes it does make a differance, and belive me when I say this, it is unsafe.

MickMc · 08-12-2009, 10:58 AM

Quote:

Originally Posted by LONGHAIR

Your metric conversion math is absolutely correct...but the difference is more than you are thinking.
5 millimeters is essentually 3/16"
The difference (english) between 6.5 and 6.69.....is .190 (not .095)
.190 is close enough to 3/16" (.187)
So, what it all comes down to is....does 3/16 matter? IMHO, yes. The wheel "might" physically fit over the lug studs, but the nuts will never tighten properly. They will bind on the edges of the taper before seating. THis will stress the studs.

Of course all of this is moot if the off-set doesn't "work"

Yes the difference is .190 but you have to divide by 2 because we are talking about a circle (1/2 as much on each side) so that's how I got .095.

Again all of this math. The real world is something different.

I did bolt on a set of late model wheels on my early model dana 60 no problems with the lug pattern but the offset stopped everything.

10 thousandths is not much in a 6.5 inch diameter space, but are late model truck wheels hub centric or lug centric?

Mick

Blazer1970 · 08-12-2009, 05:29 PM

Quote:

Originally Posted by MickMc

Yes the difference is .190 but you have to divide by 2 because we are talking about a circle (1/2 as much on each side) so that's how I got .095.

Again all of this math. The real world is something different.

I did bolt on a set of late model wheels on my early model dana 60 no problems with the lug pattern but the offset stopped everything.

Late model GM or Dodge wheels still use the same old 8 on 6 1/2" bolt circle. Late model GM 8 lug wheels will bolt up and work no problem. The issue is with Ford wheels which are 8 on 170mm.

10 thousandths is not much in a 6.5 inch diameter space, but are late model truck wheels hub centric or lug centric?

That is almost 100 thou, or a 10th of an inch. That is a lot. Ford wheels will not work on a GM truck without some kind of modification as someone described above. GM truck wheels are all hub-centric, but any 8 lug wheel with the correct bolt circle will work regardless of center hole diameter (as long as the hole is bigger than the hub).

Mick

xxx

MickMc · 08-12-2009, 05:55 PM

Quote:

Originally Posted by Blazer1970

xxx

Blazer1970
OK 10 thousandths is to much and therefore Ford wheels will not fit on 6.5 inch diameter bolt patterns.

Mick

1969 GMC · 08-14-2009, 01:49 PM

Have a machine shop drill a new 8x6.5 pattern in between the 8x170 holes.

08-05-2009, 10:40 AM	#1
fun in dirt Registered User Join Date: Jan 2007 Location: Mississippi Posts: 2,122	8 lug stud spacing I found this killer dealer on a set of wheels http://northmiss.craigslist.org/pts/1305110606.html , but don't the 8 lugs for '99 F250 use that 170?mm stud spacing instead of 6.5"? I really wish they would fit...is there any way it could work? __________________ '72 C to K20 "Cannibalizer" http://67-72chevytrucks.com/vboard/s...32#post8653432 '85 K30 "Big Nassy" [B]'85 C10 [B] "Corpse" '01 2500 Suburban ...party wagon & tow truck '06 Silverado SS...DD '06 C1500 WT...DD '07 Classic C1500 WT...DD Built & sold cause can't keep 'em all: '72 Blazer "The Bucket" http://67-72chevytrucks.com/vboard/s...d.php?t=433190 '55 Chevy straight axle gasser https://www.trifive.com/forums/showthread.php?t=173938 '69 Pro Street Chevelle http://www.chevelles.com/forums/showthread.php?t=332541 '86 M1031 CUCV http://67-72chevytrucks.com/vboard/s...d.php?t=553619

08-05-2009, 10:59 AM	#2
ghettoluxury Registered User Join Date: Apr 2009 Location: Waynesfield Ohio Posts: 1,991	Re: 8 lug stud spacing Correct they are 170mm. The only way it will work is with adapters __________________ 1949 Five Window, 1973 Step Side, 2000 Z71

08-05-2009, 08:22 PM	#3
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,142	Re: 8 lug stud spacing I saw one time where a guy that had a sweet 91 F-350 had 02 super duty 8 lug alloy wheels on it. The guy owned a machine shop and machined the wheels and added an offset slug that he also machined and was able to bolt the wheels to his standard truck. It seems like a lot of work though. __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*

08-11-2009, 12:47 PM	#4
MickMc Registered User Join Date: Feb 2008 Location: Albuquerque Posts: 359	Re: 8 lug stud spacing It seems to me that 6.5 inch bolt diameter pattern is 165.1mm And 170mm is 6.69 inch Therefore the difference in diameter is only .095 inch 10 thousandths is not very much If my math is correct The more important question will be if the backspacing is correct. The high offset wheels have a problem clearing early tie rods and brakes and... Just my two cents Mick

08-11-2009, 05:42 PM	#5
Dieselwrencher 6>8 Plugless........ Join Date: Sep 2007 Location: Prairie City, Ia Posts: 17,142	Re: 8 lug stud spacing Good input Mick. __________________ Ryan 1972 Chevy Longhorn K30 Cheyenne Super, 359 Inline 6 cylinder, Auto Trans, Tilt, Diesel Tach/Vach, Buckets, Rare Rear 4-link and air ride option Build Thread 1972 GMC Sierra Grande Longhorn 4x4 1972 Chevy Cheyenne Super K20 Long Step side tilt, tach, tow hooks, AC, 350 4 speed 1972 C10 Suburban Custom Deluxe 1969 Chevy milk truck 1971 Camaro RS 5.3 BTR STG3 Cam Super T10 1940 Ford 354 Hemi 46RH Ford 9" on air ride huge project *Tired of spark plugs? Check this out.*

08-11-2009, 07:18 PM	#7
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,507	Re: 8 lug stud spacing If you tried to run those Ford wheels on an 8 on 6 1/2" hub, the lug nuts would come loose on one side of the truck very quickly. __________________ Tim

08-11-2009, 07:20 PM	#8
ghettoluxury Registered User Join Date: Apr 2009 Location: Waynesfield Ohio Posts: 1,991	Re: 8 lug stud spacing I once had a set of 170 mm rims on a 6.5in 8lug chevy (because I was told they were 6.5in) and it had a wicked hop going down the road. So your answer is yes it does make a differance, and belive me when I say this, it is unsafe. __________________ 1949 Five Window, 1973 Step Side, 2000 Z71 Last edited by ghettoluxury; 08-11-2009 at 07:21 PM.

08-14-2009, 01:49 PM	#12
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	Re: 8 lug stud spacing Have a machine shop drill a new 8x6.5 pattern in between the 8x170 holes. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

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