Bolt on Wheel Sizing

[nolastyankee]

[?] I am planning to order a set of bolt on PSE wheels for the 289 FIA that I am building. I am looking for some input on what others of you out there have successfully put on your Unique.

I was thinking that 9.5 rear with 5.5 back spacing would be appropriate. Up front I was leaning toward 8.5 with 4.5 back spacing. However, even though our chassis was never on the road, it was wearing 15x8.5 American Racing Torque Thrust rims that measure at 4.0 backspacing. There is a small rub mark on the frame that is lined up perfectly with the tire center which makes me think something is a little off here...The tires up front are 235 60's.

Any input?

Unique 9122 - 289 FIA Cobra - The Legendary "Spence" Car

[clayfoushee]

Yankee,

The Weavers and Unique use Compomotive. Alan, at Compomotive, 800-621-8408, is extremely knowledeable about Uniques and backspace requirements, so that they fit your fender wells perfect.y. They also look very "period correct" (like original Halibrands) with the exception of the fake spinner, instead of real one.

Most use 15 inchers because that was the original look. The problem today is high-performance street tires are no longer available in that diameter and width rim (about all you can get are average BFG Radial TAs that don't stick very well. You'll probably want to stick with a 245/60 (any bigger and you'll rub against the frame at lock-to-lock) and 275/60 on the rear. That's what I run in 15 inchers, but as I said it's hard to get those bricks to hook up in a Cobra. You can do very impressive burnouts however!

I also recently purchased a set of 17 Compomotives from Alan that look just like the 15s. The advantage is you can find ultra-high performance tires that stick very well. In that set I'm running 245/45-17s front and 285/40-17 rear with Kumho Escsta MXs. I posted pictures of both over in the gallery on CobraClub or if you e-mail me, I'll send 'em directly to you. It's different and more modern look, but certainly not as vintage Cobra.

In any event, you should talk to Alan at Compomotive who is very knowledgeable about Uniques and backspace requirements. You'll find wider tires running on other replica Cobras, but the Unique frame dictates the choices I outlined above.

Clay

Unique 9299, 427FE side oiler, top-loader (close), 3.31 rear

Annapolis, MD

[Poorboy]

Is it the front tire that rubs & is it just when turned sharp?? If so most all will.
Scott Curry has had a set of wheels on order from PSE for over 4 mounts and they keep making excuses as to why he has not gotten them. Now they are never available when he calls.
I like the looks of the wheels that on your car now a lot better than the 17s. The 17" wheel just does not fill the wheel well like should. On the newer Compomotive wheels the centers do not fit the wheel. There is a 1/4" gap between the center and the outer ring. If you are not going to use the American wheels what would take for them??

Poorboy

[nolastyankee]

Poorboy,
The front tire is the one that rubs, and only on a frame corner at full lock. It isn't a huge deal, but given the original owner's mechanical skills witnessed to date, I felt pretty certain there was a good chance that the wheels/tires were sized incorrectly.

[?] So is it safe to say that frame rub is not unusual here? Is there not a limit screw on the rack that can be adjusted to prevent rub? I haven't looked that closely at the steering system yet...My first task was to pull out that horrible B&M shifter.

I plan to stay with the 15" wheels, I prefer the original look. I like the PSE's because it sounds like he would be willing to make up a set of bolt-on FIA style wheels similar to ones that Compomotive manufactured some years back. I have heard that PSE is quite unreliable on delivery, but as long as I'm not handing him the full value of the product, time is something that I have plenty of right now.

If I can't get a set of bolt on FIA's, I think the AR's will stay. Either way I will need them through the build which will likely take me into next summer. I'll keep you in mind if I do unload the AR's.

[?] One more question here...My lugs measure out to a 4.75" bolt center. I am most familiar with 4.5 and 5.0 centers, am I doing something wrong, or is this measurement correct?

Unique 9122 - 289 FIA Cobra - The Legendary "Spence" Car

[Poorboy]

There is no stop adjustment on the rack. You will only turn that far when parking and such, so it will not do any harm. All looked to be correct when I looked at it.
Your measurement is right, the bolt pattern is the same as GM mid-size, carmro, Monti Carlo, etc. Well keep me in mind if & when you get ready to get rid of them.

Poorboy

[Jim Harding]

nolastyankee wrote....." One more question here...My lugs measure out to a 4.75" bolt center. I am most familiar with 4.5 and 5.0 centers, am I doing something wrong, or is this measurement correct?"

With 5 stud pattern, measure from the near edge on one stud to the center of the opposing stud, not center of one to the center of the other. You should then see your 4.5"

- Jim -

Jim Harding
La Plata, Maryland

http://www.capitalareacobraclub.com/albums/album26/1aLeftside.thumb.jpg

[clayfoushee]

Poorboy,

I just put a new set of 17" Compomotives on and they DO fill out the wheel well almost exactly the same as he 15 inchers with tall tires. There's less than a 1/2" diameter difference between the 15 with BFG TA's described above, and the 17's with Kumhos described above. It all depends on the tire you choose. Two 245/45 tires by different manufacturers on the same wheel will likely have different diameters. I was very careful to find a combo with almost exactly the same diameter. The only visually perceptible difference between the 15 and 17 look is the amount of rubber vs. wheel filling the well.

As to your observation about the "gap," that is not the case on my set of new Compomotive 17's. There is no gap "between the center and outer ring." I'm perplexed as to what you meant.

As I said in my original post, I also prefer the "period correct" look of my 15's, and have no intention of giving them up. But, I like to DRIVE the car much better on the 17's. The 15's without ultra high performance tires just will not stick to the road in my big block car. The 17's give me a lot more confidence in the car as mine is set up.

I'd rather not have spent the money to have both sets, but at least for me it's worth it. That's all I was trying to say.

Clay

Unique 9299, 427FE side oiler, top-loader (close), 3.31 rear

Annapolis, MD

[Poorboy]

Clay,
Yours may fill the wheel wells, just the ones I have seen don't. I guess it is a matter of what you like. I just don't realy like the look of the short side wall tires. To much wheel and a rubber band for a tire, even though they handle better.
Here is a picture of the gap I am talking about. This is a brand new set that just came Monday.

Poorboy

http://www.uniquecobra.com/uploaded/poorboy/MVC-011S.JPG

[clayfoushee]

Wow!!!, I NOW see what you mean Poorboy. Mine don't have that gap...I'd send 'em back to Alan. It looks like your centers may have been from a different lot and weren't quite the right size. That doesn't make a lot of sense, because I would assume they were all cast from the same mold. I have no logical explanation.

You and I are in fierce agreement. I also prefer the 15 look, but I've been nutty about Cobras since I was 11. Most who've seen my car like the 17's much better, but they don't know squat about Cobras and are reflecting modern tastes.

I'm gonna routinely swap 'em back and forth. My main point from the beginning (I think it got lost)was that after road tests of both on the same car, the handling is dramatically better on the 17's and the beast is a little tamer. Period correct looks are important, but so is how the car performs.


Clay

Unique 9299, 427FE side oiler, top-loader (close), 3.31 rear

Annapolis, MD

[nolastyankee]

Gentlemen,
I appreciate all the information on the topic, as it provides me valuable information as I go about selecting wheels.

In the interest of pestering this topic a bit more, for all of those who are running 15" bolt-on wheels, what rim width and backspacing did you go with? Clay? Poorboy?

Thanks for the continued interest in this topic...

Unique 9122 - 289 FIA Cobra - The Legendary "Spence" Car

[clayfoushee]

I bought my car all in one piece, and the 15s came with it. I just purchased the 17s and Compomotive knew what they should be for Uniques. If you want definitive info on the proper backspacing for a Unique, I again suggest that you contact Alan at the number in my first threat above. He's been supplying wheels for Uniques for years, and has it down. Whatever they use, the rims are completely flush with the edge of the fender wells, which is the way they should be.

I'd measure the 15s for you, since they're not on the car right now, but I sent them to Compomotive to be freshened up.

Clay

Unique 9299, 427FE side oiler, top-loader (close), 3.31 rear

Annapolis, MD