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What do you think about those Rims?

  • Dang they’re sick

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Discussion Starter · #1 ·
Hi Guys,

i´ve got an 1995 Firebird Convertible with the 3.4l V6 Engine.

My Car came with stock 215/60R16 ET45 Alloy-Wheels which i want to change to 215/60R15 ET17.
I know that the original pattern is 5x120.65 (5x4.75) and the new Rims are 5x120. That´s not a huge difference between both but there is still a difference and of course you shouldnt do that. But since im using this car just to cruse around, and here in Germany you dont get 5x120.65 im just gonna stick with 5x120 although ive bought centering rings to get it even better centered.

But know to the Question, do the 15" Rims fit over the Brakes?
At front ive got original ventilated Disk-Brakes, at rear Drum-Brakes (Maybe gonna change them to Disk-Brakes someday if there is a Kit or something?).
Do the 15" Rims fit over them or am i going to have some problems here?
The stock rims have an ET of 45 the new one an ET of 17 so they are going to move out 2.8cm so im going to have a lot of clearance between the Brakes and the face of the rims. (ET is in Germany what you Guys call offset so im going to run an positiv offset and move the Rims to the outside to make the car wider).

Would really appreciate any help of you Guys!

Thanks!
Acelino
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May not fit. Does your car have rear disc brakes? I run 15” drag strip wheels. Fronts required a small spacer, rears required modifications to disc brake calipers.

Some people who have run 120mm bolt pattern on 120.65mm hub have reported broken studs and loose lug nuts. As a licensed professional (mechanical) engineer, I recommend against it.
 
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Discussion Starter · #3 ·
Hi Injuneer,

nice to hear from you again :giggle:,

at the rear i have Drum-Brakes right know but maybe im going to change them to Disk-Brakes someday.

Because of the Bolt pattern, im although an licensed professional (mechatronical) engineer here in Germany, and I understand your concerns.
But since there is no other Option here in Germany then to run 5x120 instead of 5x120.65 im going to try it an see how good they fit.
Typically they should fit right?

Locking forward to hear from you again ;)

Acelino
 

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Sure they will "fit" over the studs. But tightening the lug nuts will put bending stresses on the studs. A lot of people tell me they have run 120mm wheels (BMW wheels are popular here) with "no problems". But as noted, I have seen reports of broken studs and loosened lug nuts from others. I'll admit, I'm very conservative.

I'm assuming the wheels you are interested in have conical lug nuts. If they have a shank style lug, it could be a problem.

Did you check the hub diameter of BOTH the front and the rear wheels, to get the dimensions for the centering rings? Up until late 1996 models, the diameter of the rear axle hubs was larger than the front hubs, at least on the V8 models.

There is no way I can tell you if those wheels will "fit" over the brakes. I do not know the drum brake dimensions, I don't think I have ever seen them. And I have no idea what the profile of the inside diameter of the rim is. And without knowing the width of the wheel (you have provided tire dimensions, not wheel width), I can't tell you if they are going to rub on the fenders.

Are you saying you can't order the correct wheels from anywhere outside of Germany? Have you considered a wheel from a Corvette? They have offsets that are closer to what is run on the Camaro/Firebird, and the correct 120.65mm bolt pattern. They should be available from a GM dealer in Europe. Or, have you contacted wheel vendors in the US to see if they will ship?

To me, dropping to 15" street wheels is a step in the wrong direction.
 
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Discussion Starter · #5 ·
Hi Fred, thank you again for the reply 😋

I totally get the point with the not fitting bolt pattern, but the rims I can get with the 5x120.65 bolt pattern are much too expensive and I mean by to expensive like 2000-3000$ or they’re so ugly that I wouldn’t want to buy them haha.
They have a conical lug nut like you’ve said so that should fit 😊.
At front my wheel hub is 70.3 and at the rear ive got 74.1 I’ve bought centering rings for both, the rims are 82.0s so that should work I guess?
Acelino
 

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I want to question if you have first selected tires for the 15" wheel. Might want to start there. I'm not 100% sure you're going to find a good modern street tire for a 15". Last time I looked (years ago) almost everything was an old fashioned radial tire which isn't really appropriate on these cars aestheticly or performance-wise. ...and the industry has long since moved on. The modern vehicles that come with 15" wheels are smaller, lighter, and do not generate thr same forces on the tires as the much larger 'bird does. I assume those tires are not even load rated for a firebird and certainly won't have a strong enough sidewall.

I could be wrong, but just be sure you can get the right tire before spending any money. You could end up very disappointed to learn the only tires available in 15" are for big 70s cars, little Toyota Yaris like things, or drag strips.

My neighbor put radials on his 'bird. They looked really out of place, especially with white walls. ...and I promise they compromised handling.

Maybe Europe has more options available, I can't say I ever looked at that market. Just sharing my concerns as if I were considering this myself, which years ago, I did.

...the proper direction for us in the States is moving up to 17" or better yet, 18". Selection of 16" tires worthy of these cars is almost non-existent now, and options will only decline.

As manufacturers move to larger wheels, so does performance. It won't be very long before there is only one street performance tire left for 17" owners and us 16" owners are left out completely.

You really should consider the "future market" as well.

I have the v8, so I do need a tire with a little more grip, but trust me, a cheap tire on these cars impacts more than off the line grip, and as it stands, the BFG Sport Comp II is the last 16" tire on the market that has the correct performance metrics to match our vehicle.

Good luck with whatever you decide to go with.
 
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Discussion Starter · #7 ·
Hi ZumpTA,

thanks a lot for your reply, here in Germany it’s not a big deal to get tires, it’s more a problem with the rims. I had 215/60R16 85W on the car originally, now I’ve got 215/60R15 94H the originally 85 tires had a load rating of 515kg now I’ve got 94s that’s for up to 670kg so that should fit, you can even get some “Supersport” tires in that size but they are to expensive for now. I’ve got some Nexen tires which should be good for now, gonna change later to Dunlop or Pirelli.
Thanks a lot for all the help of you guys, I love the states and it’s awesome to talk to all of you!
See you soon!
Acelino
 

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With those tire sizes, you have reduced the outside diameter of the tire by 2.54cm. That will cause your speedometer to read 4% higher than actual speed, and your odometer to add 4% extra to the accumulated kilometers. (Unless you have the PCM reprogrammed). Did you consider using a 215/65-15 tire? That would have eliminated the error, and reduced the gap between the fender lip and the top of the tire by 1.27cm.

What width are the new 15” wheels? You could have gone up to a 235/60-15 tire and maintained the correct diameter. Although with the 17mm offset there might have been some rubbing issues, depending on how wide you went with the wheel.
 
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Discussion Starter · #9 ·
Hi Fred,

thanks again for replying :)
The Wheels I’ve got are 7.00x15” for the front and the rear, that’s because they’re an classic line here in Germany and they don’t sell them in a bigger dimension.
An other big point to not go bigger with both the rims and the tire was that here in Germany we normally have to go to an office to let them check every single thing you modify on the car. Non of the American rims pass that test not because they’re not as good, but because you don’t get any papers with them and here in Germany that guys working at that office are really d***s. They don’t let you do anything at all. So I was hoping with those rims and nearly the original tire-size the cops here would not know as often that they’re not original 😂. Here in Germany modifying cars really isn’t that nice as like for you guys in the states. Just for an example, before I’ve got the firebird I had an SN95 Mustang, everything was original on the car and I did not pass the Inspection just because the original headlight wasn’t tested in Germany, they told me I could 1. Pay them up to 1000€ to let them test, or 2. The car would not be allowed to drive on the road again. And that with OEM Parts. So if I would get there with the Bird with some nice 18” Rims and like 275/45ZR18 they would simply just laugh and send me home and the car would never drive again here 😅. Because of that I chose those rims and Tires, I was hoping that the police wouldn’t really notice, I mean the rims on the paper are nearly the same, and for inspection which we need to do every 2 Years I’m just going with the original 16” rims.
Have a nice Weekend!
Acelino
 

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If you already have the wheels and tires, why did you even ask your question???

Seems like you already decided on the choices which may: 1) compromise the wheel studs; 2) compromise vehicle handling; 3) reduce the accuracy of the speedometer/odometer. What were you expecting from us in response to this? Basically, you just wasted our time.

Very disappointed.
 

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Discussion Starter · #11 ·
Hi Fred I thing you’ve got me wrong, or maybe I just wrote that wrong, I don’t have the Rims or the Tires, I’m just in contact with an dealer here who is going to ship me both if I’m going to choose that option. The reason Ive asked the question to you guys was just because I wanted to know what you guys think about that. Sorry if that was disappointing to you guys, like I said I just wanted to know your thoughts…

Have a nice Weekend
Acelino
 

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The Wheels I’ve got…….
Sure sounds like you already have them.

Additionally, if you had explained why you had to do this in the first post, I would have gone directly to my response (technical content) in post #10, explaining why your solution was, in my opinion, incorrect.
 
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Discussion Starter · #13 ·
Yeah I understand, sorry that was my fault, by “the Wheels I’ve got…” I wanted to say “the wheels I chose for example…” sorry for that.
For the next time I’m going to start straight in, sounds like that would be better then 😊.
Anyways I really appreciate your help. Now that you know the background story with the technical inspection I have to pass here and the police looking for guys with rims that are fancy and could not be original, what would you say? Are the rims and tires I chose for example an option or are they even worse and I should stick with the original ones (using 215/65R15 or 225/65R15 like you said to help out with the incorrectness of the odo- and speedometer and going with those 15Inch rims I’ve posted on my first post here).
Thanks a lot!
Acelino
 

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Discussion Starter · #14 ·
Hi Guys its me again,

so i finally did it, i bought the rims ive mentioned above and some good tires and what should i say?
They´re fitting pretty good, ive although got my self some centring-rings to get the rims as centered as possible. Ive torqued them first to 80Nm and then to 120Nm in a criss cross pattern of course.
After making sure theyre all thight ive drove around the blocks going up to 60mph and there are no vibrations or anything so im pretty happy about it.

Thanks for all the help of you guys!
Acelino
 

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Discussion Starter · #15 ·
Here some pictures of the car with the new rims and tires, hope you guys like it!!!

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The wheels look much better than I imagined. Nice choice!
 
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