5x120mm vs 5x4.75" wheel bolt pattern

[tminer]

Which is the GTO, or are they the same?

I know that 5x120mm is the BMW spec and that most of the wheel peddlers distiguish between the two and will often label the 5x4.75" as 5x120.65mm. Did Holden/GM actually change to 5x120mm or is it just a case of semantics?

tyvm,
Tom

[tminer]

I wonder if they aren't the same 5x4.75" that GM has used for decades and just called 5x120mm because AU is metric.

Tom

[cjlannoy]

I called tires plus this morning and they said that you can't interchange the 5x4.75 for the 5x120 even though they are extremely close.

[cjlannoy]

see my post in "nice wheels"

[Homebound GTO]

Went to ROH site

5x4.72-5x120mm
5x4.75-5x120.65mm

Hope this helps.

[tminer]

I know all of that. I'm just trying to find out what the GTO actually has, 5x120mm BMW spec, or 5x4.75" that has "mistakenly" been called 5x120mm.

Tom

[Holeshot]

I checked today 5x4.75 is actually 5x120.65 mm
be carful when selecting Rims

[hada64]

I checked today 5x4.75 is actually 5x120.65 mm
be carful when selecting Rims
True. The question is does the 0.025" make a real difference or not. Some tire/wheel dealers say yes, others no.

[Tails]

Reality check here. Some some dealers are saying that you take an inch. divide it into 40 equal parts. Add one of these 1/40th of an inch parts to the spacing and everything now doesn't fit? Now I am not an expert but I have changed a few tires in my time. It seems like there is a little more slop then 1/40th of an inch when I put the wheels back on. I would like to understand what the downside is on 1/40th of an inch.

[tminer]

I would imagine that AT BEST it will depend on the lug nut style. But even with conicals, it would seem that some buggering of the seat will occur when torquing down steel nuts on an aluminum wheel.

I can't seem to make this clear, it is not an issue of crossing one to the other, but rather determining which the GTO actually utilizes. I have seen both specs given, and even from the same poster. I've seen it posted that GM and Holden are the same: 5x120mm, but we KNOW that GM (pre-GTO at least) is 5x120.65mm/5x4.75". Apparently, this is just too confusing for the average Joe.

Tom

[miamio]

My gut tells me the 5x 120 is correct. The GTO originates in a metric country so this would lead me to believe the thought that it is the same as BMW. Hey Aussies, how about a little help? What is the Monaro?

[GTOME]

I agree with tminer, The Lug nuts will not seat properly. Could eventually destroy Your nice new Wheels and inadvertnly Screw up other things such as throw your axle out of ballance, wear bearrinr prematurely and send errors to the ABS system .

[cjlannoy]

I've checked 4 different places and got four different answers, I've currently got a call into GM engineering for the specs. Nobody can tell me for sure what the correct size is and I've yet to get a "true" expert to tell me for sure if they won't interchange. This really sucks, I'd really like some better wheels and I have money burning a hole in my pocket! (I've never had to work so hard to spend $2000 in my life)

[cjlannoy]

see the "Aussie Monaro" thread. :(

[GTOME]

I've checked 4 different places and got four different answers, I've currently got a call into GM engineering for the specs. Nobody can tell me for sure what the correct size is and I've yet to get a "true" expert to tell me for sure if they won't interchange. This really sucks, I'd really like some better wheels and I have money burning a hole in my pocket! (I've never had to work so hard to spend $2000 in my life)

If your pocket gets too hot, let me know. I'll be glad to takke that 2K off your hands. ;)

[cjlannoy]

for a nice set of tires and wheels its all yours

[GTO_Again]

I've checked 4 different places and got four different answers, I've currently got a call into GM engineering for the specs. Nobody can tell me for sure what the correct size is and I've yet to get a "true" expert to tell me for sure if they won't interchange. This really sucks, I'd really like some better wheels and I have money burning a hole in my pocket! (I've never had to work so hard to spend $2000 in my life)

I don't know how accurate / factual this is - -

o Listen up aftermarket wheel manufacturers! The 2004 GTO lug spacing is not a traditional American size so existing aftermarket wheels for GM cars won't fit.

Source:

http://www.highperformancepontiac.com/features/040 4pon_yellowgto/

[miamio]

I saw this on another site:

The kind people at Pontiac asked that I post the following info to me on the GTO's wheels.

The GTO hub has a 5x120.00mm bolt circle diameter.
The offset is 48 mm for both 17-inch and 18-inch wheels.
The GTO wheels have 8.0 inch wide rims.

[DevilYellow]

Yea, Pontiac sent me the same info ... Howie has posted the wheel details for quite some time. That is why I did not repost it.

[tminer]

I saw this on another site:

The kind people at Pontiac asked that I post the following info to me on the GTO's wheels.

The GTO hub has a 5x120.00mm bolt circle diameter.
The offset is 48 mm for both 17-inch and 18-inch wheels.
The GTO wheels have 8.0 inch wide rims.
Thank you sir!

Tom

[tminer]

Yea, Pontiac sent me the same info ... Howie has posted the wheel details for quite some time. That is why I did not repost it.
Yea, I'd seen his post but there was no reference to the source. There have been many different posts on various boards and several wheel dealers have the pattern listed but all seemed to split about 50/50 between the two patterns. Kind of hard to know whom to trust.

Tom

[GTOJer]

I saw this on another site:

The kind people at Pontiac asked that I post the following info to me on the GTO's wheels.

The GTO hub has a 5x120.00mm bolt circle diameter.
The offset is 48 mm for both 17-inch and 18-inch wheels.
The GTO wheels have 8.0 inch wide rims.

Are we sure about the 48mm offset? That is only 1.89" if my math is not failing me. It sure looks like more than that.

[tminer]

That is the centerline offset, but the two "halves" will be twice that different in size. It works out to about 6" backspacing. There isn't a direct correlation because of the way the two specs are measured (0 offset on an 8" wheel isn't 4" backspacing).

HTH,
Tom

[Howie]

Yea, I'd seen his post but there was no reference to the source. There have been many different posts on various boards and several wheel dealers have the pattern listed but all seemed to split about 50/50 between the two patterns. Kind of hard to know whom to trust.

Tom

We actually did wheel & tire test fitting. Beside if you takes off any wheel from your GTO and look on the inside it'll give you the factory wheel specs.

17x8 with 48mm backspacing

Arrowhead Performance has the correct wheel specs to fit a 9" wide wheel on the back and use a 275 series tire. Up front you are limited to a 8" wide wheel and a 245 series tire.

Feel free to contact me for more info.

[cjlannoy]

I thought this might be interesting because I know at least I thought that back spacing and offset were the same thing, (turns out I was wrong) see below:

Q: What is wheel backspace?
A: Backspace is the distance from the back edge of the rim to the mounting surface on the hub.


Q: What is wheel offset?
A: Offset is the distance from the wheel centerline to the mounting surface. Positive offset is when the mounting surface is outside the centerline. Negative offset is when the mounting surface is inside the centerline.

[tminer]

Yep, and what makes 0 offset not equal to 4" backspace on an 8" wheel is that the center line and mounting surface (same for 0 offset) are 4" from the inside of the back lip but backspace is measured from the outside of the rear lip.

Backspace is width/2 in mm (in x 25.4) + offset + 6 and then divide by 25.4 to get inches.

Offset is backspace - 1/4" - width/2 and then multiply by 25.4 to get mm.

Our 8" wheels with 48mm offset should be 6 & 1/8" backspace.

The 6mm and 1/4" represent the lip width and are just typical values.

HTH,
Tom

Edited 6 & 1/4 to 6 & 1/8. Calc'd 6.125, and blew the conversion.

[tdimasi]

There has been much discussion about whether a 5 x 4.75" pattern/wheel will interchange with the GTO's 5 x 120mm specs. For what it's worth, American Racing (www.americanracing.com) just updated their website with 2004 GTO Applications. Only 2 or 3 wheels, but all are listed as 5 x 4.75."

[tdimasi]

Received a call from a trusted friend in the aftermarket wheel business. Word from American Racing and Weld is that they won't be tooling up for GTO wheels. 18K units per year doesn't translate into enough sales to make production worthwhile.

Still can't figure out why ARE lists a few wheels (4.75") on their web-site. This recent addition conflicts with quite a bit of other info. Specifically, liability issues associated with using 4.75" wheels on 120mm hubs.

[nikivee]

Another tire and wheel company has fitted wheels and tires and claims that the bolt pattern is 5x4.75 standard GM pattern. Geez more confusion.

[nikivee]

I'm going to do my own testing this weekend. I have some 17" Boyd wheels from a Camaro. I will test fit those and post back here.

[AZ Power and Sound]

The answer is 5-120.65 or 5-4.75. Tested by me, verified by my technical department.

You will find people that say it doesnt matter either way. 5-120 and 5-120.65 but it CAN make a difference. Maybe 1-10,000. Maybe more. Either way...do you want to be that one person that has a wheel come off of the car at highway speeds when you and your family are driving???

Do it right the 1st time.

[cjlannoy]

Actually I contacted Jim Hopson at Pontiac and he got me the info that says the wheels are 5x120 and 48 mm offset 18x8" wheels. Whether they can or should be interchanged I have no idea. I currently have Motegi Kruz wheels on my car and they are 5x120. See link.
http://www.ls1gto.com/forums/showthread.php?t=1674

[yourguyry]

hey, i want to use 18x9 rear, and 18x8 front. what are the exact sizes i should use.. tire, backspacing? Howie i would like to know what you think since i know you have done much work on rims and sizing for the GTO. Thanx

[Howie]

hey, i want to use 18x9 rear, and 18x8 front. what are the exact sizes i should use.. tire, backspacing? Howie i would like to know what you think since i know you have done much work on rims and sizing for the GTO. Thanx

Shoot me a PM or email. I've got what you want and have a current group purcahse going for 18" Intro wheels. Thanks!

[Homebound GTO]

Howie,
Not to change the subject, but we ordered a set of ROH rims from you on February 10th. Please let us know when they are ready to be shipped.

[Howie]

Howie,
Not to change the subject, but we ordered a set of ROH rims from you on February 10th. Please let us know when they are ready to be shipped.

I'll check on it in tomorrow. Normal build time for the Stradas is 6 weeks.

[Homebound GTO]

Hi Howie,
Thanks for checking on our rims tomorrow, however, they are Modena's.

[AZ Power and Sound]

I was able to quadruple check and it seems as if the 1st measurement was wrong and the GTO is indeed a 5-120.

Grrrr!

[kenchen]

Both front and rear spacing are measured from the outside lip of the wheel and combined is one inch wider than the tire mounting surface width. So - an 8" wide wheel with 0 offset would have both a front and rear spacing of 4.5".

The spacing on the stock wheel with +48mm offset is front 2.61" and rear 6.39" for a total of 9 inches. To get this, ADD 48mm (1.89") to the center of the wheel (4.5) to get 6.39" rear spacing. To find the front spacing, simply SUBTRACT 1.89" from 4.5" to get 2.61". Another way, if you have the rear spacing, subtract that spacing (6.39") from the overall width of the wheel (9") to get 2.61" All very simple, right?

Yep, and what makes 0 offset not equal to 4" backspace on an 8" wheel is that the center line and mounting surface (same for 0 offset) are 4" from the inside of the back lip but backspace is measured from the outside of the rear lip.

Backspace is width/2 in mm (in x 25.4) + offset + 6 and then divide by 25.4 to get inches.

Offset is backspace - 1/4" - width/2 and then multiply by 25.4 to get mm.

Our 8" wheels with 48mm offset should be 6 & 1/8" backspace.

The 6mm and 1/4" represent the lip width and are just typical values.

HTH,
Tom

Edited 6 & 1/4 to 6 & 1/8. Calc'd 6.125, and blew the conversion.

[jasonblair]

Nothing like a response 18 months after the last post! ;)

[cjlannoy]

wow, I haven't gotten an email in a long time from here. :eek2:

[St.Mary]

Ahhh, but the question still lingers. Will they work.

I say as long as they are hubcentric :thumbs: but good luck with finding rings.

The lugs are just there to hold the wheel to the hub and to transmit the torque to the wheel. The centering issue should be taken care of with hub rings.

Edit: This is my opinion. I am not a technician and have never tested these (I'm po'!) However, if someone gave me a set of camaro rims, with hubcentric rings, I would put them on and not think twice about it!

[Flashpoint]

Ahhh, but the question still lingers. Will they work.

I say as long as they are hubcentric :thumbs: but good luck with finding rings.

The lugs are just there to hold the wheel to the hub and to transmit the torque to the wheel. The centering issue should be taken care of with hub rings.

Edit: This is my opinion. I am not a technician and have never tested these (I'm po'!) However, if someone gave me a set of camaro rims, with hubcentric rings, I would put them on and not think twice about it!


I would tend to go with this also, hubrings or at the very very least, torquing the lugs down with a tq wrench in a 3 step star pattern. NOT the air tool zip them all down method.

If you get vibration at any speed and the wheels are balanced...it isn't centered right on the hub.


Personally, I'm getting 5x120 wheels with pressed in aluminum hubrings.

[sccaGTO]

I would tend to go with this also, hubrings or at the very very least, torquing the lugs down with a tq wrench in a 3 step star pattern. NOT the air tool zip them all down method.

If you get vibration at any speed and the wheels are balanced...it isn't centered right on the hub.


Personally, I'm getting 5x120 wheels with pressed in aluminum hubrings.
And when is ROH gonna get around to making those?

How the hell did this thread get restarted??? I guess it could be worse. Someone could have started this topic in a new thread.

[Flashpoint]

And when is ROH gonna get around to making those?

How the hell did this thread get restarted??? I guess it could be worse. Someone could have started this topic in a new thread.


They are suppose to have the 9" wide wheels here in 2 weeks. What sucks is, I will get them in my hands and then most likely put the car away for winter a few eeks later :mad:

I might not even bolt them on till spring, why have the car sit in the garage with the aftermarket wheels on.

[sccaGTO]

They are suppose to have the 9" wide wheels here in 2 weeks. What sucks is, I will get them in my hands and then most likely put the car away for winter a few eeks later :mad:

I might not even bolt them on till spring, why have the car sit in the garage with the aftermarket wheels on.
Good point. That means you can push back the tire purchase. Maybe a better tire will be introduced in that time.

[LS1billy_goat]

if only AR Rebels would fit =\

[CoppeR]

I would never go anything but 5x120. How ever IBM/M6 got Motegi's w/ a 4.5bolt pattern mounted

http://www.ls7gto.com/forums/showthread.php?t=4928 8&highlight=motegi

[Trapper]

As I also own a Grand Prix, and participate in the forums on Grand Prix clubgp.com, this is sounding very familiar. The numbers there are slightly different, as GM says the GP has 5 x 115. If you look at TireRack, they have 20 or so wheels listed at that pattern, and almost 100 at 5 x 114.3, a common size for Japanese imports. That difference is .70mm, and our GTO difference is .65mm., so mighty close to the same variation.

I have had both patterns on my GTP and could not tell the difference. Also, a friend of mine has a BMW, and a 1967 GTO. Just for kicks he put the BMW wheels (120mm) on the old GTO, which is 4.75 inch, and they bolted up just fine.

I am old enough to have been working at GM in engineering when the metric conversion was first started. We had many hand-assembled fasteners (plastic push-pin types) that called for a hole size of 1/4 inch. The metric conversion went in and changed all the specs and drawings to say 6.35mm. No tooling changed, no parts changed, just the numbers.

I do agree with miamio that as AUS is a metric country, the GTO wheels probably are 120mm. The question is, will that really matter?

[miscreant]

As I also own a Grand Prix, and participate in the forums on Grand Prix clubgp.com, this is sounding very familiar. The numbers there are slightly different, as GM says the GP has 5 x 115. If you look at TireRack, they have 20 or so wheels listed at that pattern, and almost 100 at 5 x 114.3, a common size for Japanese imports.Not to be combatitive, but perhaps you could list one of those 100 wheels that are supposedly 5x114.3. I know a couple guys at the rack, and they have a policy they will NOT sell any other bolt pattern than is stamped on the back of the stock wheel. A quick search through the myriad of wheels listed as GTP fitment shows all of them as 5x115...

This is an old thread. The subject has been beat to death for over 10 years now.

[Trapper]

Not to be combatitive, but perhaps you could list one of those 100 wheels that are supposedly 5x114.3. I know a couple guys at the rack, and they have a policy they will NOT sell any other bolt pattern than is stamped on the back of the stock wheel. A quick search through the myriad of wheels listed as GTP fitment shows all of them as 5x115...

This is an old thread. The subject has been beat to death for over 10 years now.


I agree that they won't sell it for a GP. They will sell it for something that has 114.3 from the factory, like a Honda. The "100" wheels in 114.3 are not for GP's, but listed for other cars that come with 114.3 standard. I just checked the Tire Rack site, put in a 2004 Honda Accord, and it listed 107 wheels.

If you buy a 114.3 wheel from TireRack that you have looked up as fitting a vehicle that came with 114.3, they don't come to your house to see what you put it on.

I understand their concern over liability, and presume that is why they take this position. That is also probably why they list six wheels for a GTO and about 56 for a BMW 3-series. I believe I have read posts on this forum from people who purchased BMW wheels from the TireRack, only to put them on their GTO. Once they ship the wheels, you can put them on what you want. It justs eliminates the TireRack from liability should anything go wrong.

[IBM/M6]

I would never go anything but 5x120. How ever IBM/M6 got Motegi's w/ a 4.5bolt pattern mounted

http://www.ls7gto.com/forums/showthread.php?t=4928 8&highlight=motegi
actually I dont really know what they are . this is a really old post but the guy I bought them from is cjlannoy . his post re: these wheels is in this very tread from last year . they are 5x120

cjlannoy Actually I contacted Jim Hopson at Pontiac and he got me the info that says the wheels are 5x120 and 48 mm offset 18x8" wheels. Whether they can or should be interchanged I have no idea. I currently have Motegi Kruz wheels on my car and they are 5x120. See link.
http://www.ls1gto.com/forums/showthread.php?t=1674

[miscreant]

I agree that they won't sell it for a GP. They will sell it for something that has 114.3 from the factory, like a Honda. The "100" wheels in 114.3 are not for GP's, but listed for other cars that come with 114.3 standard. I just checked the Tire Rack site, put in a 2004 Honda Accord, and it listed 107 wheels.

If you buy a 114.3 wheel from TireRack that you have looked up as fitting a vehicle that came with 114.3, they don't come to your house to see what you put it on.

I understand their concern over liability, and presume that is why they take this position. That is also probably why they list six wheels for a GTO and about 56 for a BMW 3-series. I believe I have read posts on this forum from people who purchased BMW wheels from the TireRack, only to put them on their GTO. Once they ship the wheels, you can put them on what you want. It justs eliminates the TireRack from liability should anything go wrong.I misread your post as saying they listed 100 wheels in 5x114.3 for the GTP.