I say 4.75" wheels bolt up just fine

[nikivee]

I know that this debate about bolt patterns with the new GTO has been going on for over a year so I won't rehash it here. What I do know is that I'm not convinced that a "chevy", 4.75" bolt pattern doesn't work.

I will state that it does fit with NO problems. I've test fit wheels before and just did it again today, and measured again today. I myself would have no problem buying a 4.75" wheel with proper offset and putting them on my GTO with no fear of the wheels falling off or cracking. In fact I'm going to call American Racing and see if they can get me the proper offset for the Torque Thrust II wheels and purchase a set with the 4.75" bolt pattern.

Here are some pics for you guys of my fitment test.

Pontiac 14x6 Rally II wheel on front
http://images7.fotki.com/v150/photos/4/42075/74195 9/DSC00099-vi.jpg
http://images7.fotki.com/v149/photos/4/42075/74195 9/DSC00093-vi.jpg
http://images8.fotki.com/v154/photos/4/42075/74195 9/DSC00096-vi.jpg
http://images8.fotki.com/v154/photos/4/42075/74195 9/DSC00098-vi.jpg

http://images8.fotki.com/v155/photos/4/42075/74195 9/DSC00100-vi.jpg

Boyd 17" wheels Chevy bolt pattern

http://images7.fotki.com/v149/photos/4/42075/74195 9/DSC00101-vi.jpg
http://images8.fotki.com/v155/photos/4/42075/74195 9/DSC00102-vi.jpg

http://images7.fotki.com/v151/photos/4/42075/74195 9/DSC00105-vi.jpg
http://images7.fotki.com/v152/photos/4/42075/74195 9/DSC00109-vi.jpg
http://images8.fotki.com/v154/photos/4/42075/74195 9/DSC00106-vi.jpg

lugs nuts seated 100% centered on the wheel studs.

I know all the experts will say otherwise, but I don't buy it. .6mm difference is cancelled out by the amount of play between the wheel hole and wheel stud.

So take it FWIW.

[CSiJason]

I've basicly felt the same all along myself... The difference is 0.0235" which is probably about the thickness of a paint finish on the wheel which is likely to flake off over time around the lugs seats. I'd say, so long as the wheels are hubcentric or have a hubcentric ring in them, it shouldnt move around anyhow and I highly doubt with 80-90ft/lb of torque on each lug they will back out on their own.

[Doric]

I'd like to know how you managed to get a 14" rim over the front brakes. :sneaky:

[nikivee]

Agreed! So as far as I'm concerned, 4.75" wheels fit the 04-05 GTO's. I already know of a few 04 GTO's that are using "chevy" wheels with no issues after hundreds of miles of driving.

[nikivee]

I'd like to know how you managed to get a 14" rim over the front brakes. :sneaky:

Didn't even think about that until you just mentioned it. :D The wheel even rotated without any interference. I think the front brakes rotors are only 10" in diameter, with maybe aound 1.5"-2" for the brake caliper.

By the way I like your website!!! Very well done!!

[PadreGTO]

Have you taken it over 120mph?

I noticed a big difference between my stock rims and my hubcentric TSWs. They were smooth up to 160mph.

My new OZ rims are not hubcentric, and the few times I've taken them over 120mph I did not feel safe.

I'd like to see you take those rims to one of the high-end tire/wheel places and have them load/speed test it at 130mph and see if you're still happy.

FWIW, Padre

[nikivee]

Those rims were used only to test bolt pattern compatibility.

[PadreGTO]

Those rims were used only to test bolt pattern compatibility.
I know, but will that difference of 0.0235" cause some problems with balance at high speeds?

But if true, it would be a whole lot easier to find 4.75" bolt-pattern 15" rims for my drag tires. :)

Padre

[nikivee]

With that small of a measurement? I highly doubt it.

[PadreGTO]

With that small of a measurement? I highly doubt it.
Again, I'm just speaking from experience. The play on my OZ rims is about 1.5mm. Eyeballing it, they look lined up perfect. But over 120mph and there's a noticeable shake.

0.0235" is 0.65mm per lug. If it's misaligned to one direction, you could be as much as 1.3mm off.

Not doubting, just want to get it right. Once Jason gets me my centering rings, I'm going to take mine for a high-speed load-balanced test at 130mph. It would be interesting to do that with a set of 4.75"'s.

Padre

[nikivee]

I hear what your saying. And I'm willing to bet with these differences in measurements with properly balanced wheels, tires and centering rings on a "chevy" wheel you'll be fine.

I will find out after I order my Torque Trust II's and go for a high speed ride. I'm betting the ride will be fine. I'm will ake the risk and find out.

[miscreant]

I'm not sure it's ever been suggested that 5x120.65's don't "fit", they do. And I'd much rather bolt on a 120.65 wheel that WAS hubcentric, over bolting up and 120 that WASN'T. However, all things equal, a 5x120 is a sure and proper fit. Anytime you move away from hubcentric and 120, you risk problems, period. I've seen many people run slightly-off bolt pattern wheels for the summer, run hard on them, and then switch back to correct-pattern wheels for winter and get shakes like noone's business because they bent the lug bolt in or out..

[miscreant]

I hear what your saying. And I'm willing to bet with these differences in measurements with properly balanced wheels, tires and centering rings on a "chevy" wheel you'll be fine.

I will find out after I order my Torque Trust II's and go for a high speed ride. I'm betting the ride will be fine. I'm will ake the risk and find out.
the other problem is FINDING truly hubcentric rings.

And ~.02" may seem small, but things are amplified exponentially with rotating masses...

[nikivee]

Well, we shall find out soon.

[TrakDay]

I can't wait to hear the outcome of this. I guess I will just do the heads/cam package and hold off on the wheels until I know if this works or not.

[Striped04]

If this turns out OK, I bet American Racing is going to be selling a whole bunch of Torque Thrust II's!

[CSiJason]

the other problem is FINDING truly hubcentric rings.

I'm having a number of sets made to fit 'BMW' style wheels to the GTO. Padre gets to be the first tester.

[Doric]

Didn't even think about that until you just mentioned it. :D The wheel even rotated without any interference. I think the front brakes rotors are only 10" in diameter, with maybe aound 1.5"-2" for the brake caliper.
I thought they were bigger - like almost 12" in diameter?
By the way I like your website!!! Very well done!!
Thanks. :cool:

[ZD1]

If this turns out OK, I bet American Racing is going to be selling a whole bunch of Torque Thrust II's!

yep yep yep

[srice555]

Again, I'm just speaking from experience. The play on my OZ rims is about 1.5mm. Eyeballing it, they look lined up perfect. But over 120mph and there's a noticeable shake.

0.0235" is 0.65mm per lug. If it's misaligned to one direction, you could be as much as 1.3mm off.

Not doubting, just want to get it right. Once Jason gets me my centering rings, I'm going to take mine for a high-speed load-balanced test at 130mph. It would be interesting to do that with a set of 4.75"'s.

Padre

Let me get this right. You are expressing concerns over the log bolt pattern sizing based on your experince of a hubcentric wheel when the rings weren't installed, but the bolt pattern was the same as stock?

I'm sorry, but I can't see how this is even valid for this thread. You are simply pointing out that hubcentric wheels need the rings to be installed or the wheel will shake. Who doesn't know this already?

If you had different bolt pattern on a hubcrentric wheel and they shake, then that would be something interesting to note. However, like you said, the play without rings is a good bit which is closed to what I have experinced with a set of OZ's for my Acura RSX. Without the ring they'll move all over the place. With the rings, they aren't going anywhere.

So, I can't see a reason why a 4 3/4 inch "chevy wheel" would not work on a GTO IF the wheel is 1) hubcentric and 2) correct sized centering rings are installed.


0.0235" is 0.65mm per lug. If it's misaligned to one direction, you could be as much as 1.3mm off.


The measurement is not per lug, but total measuring circle. The different in "play" per lug for a 120.6 on a 120 hub would be no more then 1/2 the different or only 0.3mm (0.011") in this case, if there was only four lugs. With five lugs, the different is even less then that!

[srice555]

The different between the lug spacing is the same as a 13mm wrench on a 1/2 inch bolt.

[nutiger]

I also believe the bolt pattern difference won't mean squat. I do believe that the wheel should be hubcentric if that's what the manufacture set up. I had a set of Boyd wheels on my Caprice that were the correct bolt pattern but not hubcentric. At over 80 mph I started feeling a slight vibration. At over 110 MPH the car started dancing around even though the vibratition didn't getting any worse (not a good feeling).

I come to the conclusion hubcentric wheels are very important on these cars.

I have a set of TSW wheels that will be get hubcentric rings pressed in.

[nikivee]

What size is the hub on the 04 GTO's. I forgot to measure it. I will need this info when I tallk to American Racing this week.

[LiqTenExp]

69.5mm if i remember correctly.

[nikivee]

Thanks.

[PadreGTO]

What size is the hub on the 04 GTO's. I forgot to measure it. I will need this info when I tallk to American Racing this week.
What were the size of the hubs on the Rally II wheels? It seems that the 69.5mm on the Goats is not very common (which is why there are no centering rings commonly available to match them up to the BMW 72.5mm aftermarket rims, and why Jason is working on a custom set for me).

Padre

[CSiJason]

The different between the lug spacing is the same as a 13mm wrench on a 1/2 inch bolt.

Good call, I do that all the time... GO METRIC!

Anyhow, i'll have 69.5mm >> 72.5mm hubcentric rings available in about a month or so. (by April at least) This seems to be the most common size most will need seeing as most aftermarket wheels that fit the GTO were designed to work on BMW's and most BMW's use a 72.5mm hub. The rings will be made of billet 6061 aluminum (T6) and will fit perfectly over the stock hub and should fit nicely into the aftermarket wheels. I've found some BMW's use a 74mm hub which I may need to make some of, but not until their is a need.

Padre will be getting my first set of hubcentric rings for his OZ wheels to test. Due to the cost to make these, they will probably be about $80 a set shipped but well worth the cost since they should last forever.

[sccaGTO]

The different between the lug spacing is the same as a 13mm wrench on a 1/2 inch bolt.
Thank you for putting that into terms I can understand. I interchange those 2 sizes at work all the time for adjusting tie rods at work. I can now feel more comfortable about looking for some 'Vette rims for the GTO.

[nikivee]

Tell me why a hubring is required. On my old school muscle they do not have hubrings and I dont' expericence any vibrations at high speeds. Before you say, "well you old cars won't do 160mph". Your right they won't. But I've had them up over 110 many a time. My 67 will trap at 116 in the 1/4 mile and that baby is one smooth ride. I did not experience massive wheel vibrations. I don't plan on driving my 04 GTO at over 120mph for any sustained period of time.

With 80-90ftlbs applied to each lug nut, I dont' see how the wheel moves. What am I missing. I'm old school.

[miscreant]

Tell me why a hubring is required. On my old school muscle they do not have hubrings and I dont' expericence any vibrations at high speeds. Before you say, "well you old cars won't do 160mph". Your right they won't. But I've had them up over 110 many a time. My 67 will trap at 116 in the 1/4 mile and that baby is one smooth ride. I did not experience massive wheel vibrations. I don't plan on driving my 04 GTO at over 120mph for any sustained period of time.

With 80-90ftlbs applied to each lug nut, I dont' see how the wheel moves. What am I missing. I'm old school.
The hub ring assures that you bolt the wheel on centered. It's not about the wheel moving after being bolted down, it's about the wheel not being bolted on exact center. And also, a sport suspension car with low profile tires will translate wheel vibrations into the cabin more than a smoother riding car with higher profile tires.

[traumadog]

What were the size of the hubs on the Rally II wheels? It seems that the 69.5mm on the Goats is not very common (which is why there are no centering rings commonly available to match them up to the BMW 72.5mm aftermarket rims, and why Jason is working on a custom set for me).

Padre

Are these rings going to be commonly available? If so, I'd be interested.

[srice555]

Tell me why a hubring is required. On my old school muscle they do not have hubrings and I dont' expericence any vibrations at high speeds. Before you say, "well you old cars won't do 160mph". Your right they won't. But I've had them up over 110 many a time. My 67 will trap at 116 in the 1/4 mile and that baby is one smooth ride. I did not experience massive wheel vibrations. I don't plan on driving my 04 GTO at over 120mph for any sustained period of time.

With 80-90ftlbs applied to each lug nut, I dont' see how the wheel moves. What am I missing. I'm old school.

The main different is where the wieght is. On lug centric, most of the weight is on the lugs and thus the lugs studs are larger (5/8 on my 73 Charger). Hubcentric, most of the wieght is on the hub (13mm (1/2 inch) on my RSX) , and the lug studs are smaller. On lugs centrtic wheels, if you toque the wheel down with the car off the ground, then you shouldn't have a problem. Also the lugs will have a greater seat angle. The stock lugs on my RSX are almost less then 45 degrees, where my charger is more then 45 degrees.

But basic, it really doesn't mean squat if you put 90 pounds with the wheels off the ground.

May I note that padre also takes his wheels to butler? When I took my OZ to them, they did the worst job balancing I have ever felt and they used rim wieghts!!! Hello?! OZ's are alloy wheels!! Rim wieghts are for STEEL wheels. And get this, they put three 2oz wieghts on the outside of one wheel and two 1 1/2 oz on the inside! I took them to wheels direct in stockbridge who slapped on only 2oz on the outside. I would think the tech was just dumb but then I saw a Benz rolling on 20's with rim wieghts on their 130 mph balancer.

I don't know if it has anything to do with it, but i'm just saying i'm not letting another tire company that sounds like a body part touch my wheels.

[READYtoROCK]

Ok..........................all this is getting confusing to me. :eek2:

Whenever I ordered custom wheels for a vehicle of mine all I had to do was tell them the width, diameter and the make, model and year of the vehicle. I never had to be concerned with telling them the bolt patterns and offsets. That is obviously not the case with the GTO.

For safety purposes we have to use hubcentric rings on any aftermarket wheels we buy? There are some realy nice Boyd Coddington rims I have an eye on and am thinking about getting them this spring.

Do I have to tell Boyd Coddington that I need some hubcentric rings with the custom wheels? If so, do I have to tell them the size of the rings or will they know? :confused: :confused: :confused:

[Black04GTO]

May I note that padre also takes his wheels to butler? When I took my OZ to them, they did the worst job balancing I have ever felt and they used rim wieghts!!! Hello?! OZ's are alloy wheels!! Rim wieghts are for STEEL wheels. And get this, they put three 2oz wieghts on the outside of one wheel and two 1 1/2 oz on the inside! I took them to wheels direct in stockbridge who slapped on only 2oz on the outside. I would think the tech was just dumb but then I saw a Benz rolling on 20's with rim wieghts on their 130 mph balancer.

Rim weights are not always for only steel wheels. There are hammer-on wheel weights specifically made for alloy wheels. As a matter of fact, there are different shape clips, and angles of alloy wheel weights for different manufacturers and so on. By your logic, every chevy 1500 that has aluminum wheels should have stick on weights applied to the inside of the wheels, which is not the case.

On the other hand, you are correct, tire shops are "supposed" to use their better judgement on this. Ok a 97 Grand Prix, 80K and stock aluminum wheels, use the hammer on wheel weights. A 2004 GTO, with a set of aftermarket, high dollar wheels, use the stick on weights.

Another thing that tire shops fail to do sometimes is line the valve stem up correctly on the tire itself. I would say 90% of the new tires off the shelf have a paint dot on the sidewall of the tire. This is there for a reason. In theory, you are supposed to line this paint dot up with the valve stem to get the best balance on the tire. Few shops do this because of lack of knowledge, or time factors.

[sccaGTO]

It sure would help me installing the tires if they put the dot on both sides of the tire. Even if you look under the tire to line them up, they still move. You can't see that it moved until the tire is mounted to the wheel.http://img.photobucket.com/albums/v642/SCCAG TO/rant.gif

[srice555]

Rim weights are not always for only steel wheels. There are hammer-on wheel weights specifically made for alloy wheels. As a matter of fact, there are different shape clips, and angles of alloy wheel weights for different manufacturers and so on. By your logic, every chevy 1500 that has aluminum wheels should have stick on weights applied to the inside of the wheels, which is not the case.

On the other hand, you are correct, tire shops are "supposed" to use their better judgement on this. Ok a 97 Grand Prix, 80K and stock aluminum wheels, use the hammer on wheel weights. A 2004 GTO, with a set of aftermarket, high dollar wheels, use the stick on weights.

Another thing that tire shops fail to do sometimes is line the valve stem up correctly on the tire itself. I would say 90% of the new tires off the shelf have a paint dot on the sidewall of the tire. This is there for a reason. In theory, you are supposed to line this paint dot up with the valve stem to get the best balance on the tire. Few shops do this because of lack of knowledge, or time factors.

I did not know about the dot, but it makes sense. The shop I take my wheels to has a hunter GSP9700 Road Force balancer (http://www.hunter.com/pub/product/balancer/index. htm) which apply "road force" to the tires during balancing. The machine tell the tech how much to rotate the tire on the wheel to reduce wheel wieght. They must start by mounting the tire lined up with the valve stem, because the dots you mentioned on the two most recent mounted tires are withen three inches of the stem.

The balance with this machine is outstanding even at 140 MPH. And it doesn't cost an arm and leg!