Classic Maserati - Modern wheels

FWIW, my car has 16" Compomotives and are as follows:

16X8.5 Front with 225/55/16
16X9.5 Rear with 255/50/16

The original OD for at 215/70-15 is approximately 26.8in. That size is really only available in light truck sizes today. My tires are almost exactly 1in smaller in rolling diameter than the original size.

I wanted a staggered size to balance the rear weight bias of the bora, and finding a staggered set in a pair of 17s was just as difficult as in 16s. I finally satisfied myself that there are enough Mustangs in the world to keep the 16in tire in business in those sizes for a while.

IMHO, I tend to prefer the original Campagnolos best of all, but Bob is absolutely right in that it isn't enough tire for the car and the XWX is a foul handling tire. Those are on my original wheels only for car shows and the like. Otherwise, the new tires make the driving experience a world better.

 

Ron, would you please post some pictures.

Ciao,
George

 

Humm, interesting. The P4000 Super Touring that I have on the Miura don't seem to behave that way, even on hard driving. As I said, maybe you drive harder than I do and maybe I just have not reached that limit, but so far I've not had the sensation you describe. Anyway, my only additoinal comment is to make sure your tires say Super Touring on the sidewall to make sure we are talking the same tire. I concur that the XWX's are not a good tire as far as I am concerned, specially for the price they ask for them. maybe period correct for some cars, but they are not the right tire if you actually drive the thing.

Best,
Alberto

 

I've been checking tire sizes. 17" looks like the size to go with .... lots of good selections. The 16" tires appear very limited.

Ciao,
George

 

You all highjacked my thread you buggers!

Modern Maserati (3200 onwards),

Wire wheels!

Come on - some-one must have done.

Bax.

 

OOPS - Sorry Guys!!

http://www.ferrarichat.com/forum/showthread.php?t=229357

 

Although that is a very old thread, I will ask my question here as it seems to me spot on.

I have an Indy 4900 with 7.5x15 Campagnolo Starbust mag wheels and I wish to source modern aluminum wheels to avoid using the old mag's and paying the silly price of new Michelin XWX's.

Btw, I found a unique source in Europe offering that Campagnolo design, already mentioned in this forum, Heinbrand (also available at the Candini shop), but they are not very responsive, apparently making new wheels only on batches when they have enough orders, and at a stratospheric price, 1200 Euros + VAT per wheel!
http://www.finecars.cc/en/detail/car/451485/index.html?no_cache=1&ret=63

Nowadays there are a number of shops that propose custom vintage wheels, however not with the specific Campagnolo Starbust design.
Many of them propose the classical BBS RS design in several dimensions (from 15" to 17") with PCD and CB on request to fit our Maser's.
In UK, for example, Imagewheels offers 3 pc. RS replicas with either a molded center and spun/forged lips/barrels, or 3 pc. RS with a billet CNC machined center and the same spun/forged lips/barrels for a price per completely finished 8J16 or 8J17 wheel of GBP 310-320 (molded) and GBP 420-450 (billet) respectively.
- molded: http://www.imagewheels.co.uk/brs-alloy-wheel/
- billet: http://www.imagewheels.co.uk/billet-85-alloy-wheel/

This seems to me reasonable, considering that we are talking of forged wheels that are substantially more robust and lighter than only cast wheels.
8J wheels also seem to me wide enough for an Indy and could take 225/60 R16 or 225/55 R17 tyres, depending on the 16" or 17" diameter of the wheel, which are dimensions with the same rolling perimeter than the 215/70 R15 standard fitment.

My question is which rim diameter to choose, taking into account that there is a more limited choice of 16" tyres (that may even vanish in the future) but that 17" tyres will give a harsher ride not fitted to the classic car suspensions, and maybe a too modern and awkward stance to the car (even more on an Indy compared to a Merak or Bora).

Thanks to provide me with any experience or useful advice.

I reproduce here under pictures seen on this forum of a Bora on 17" and another one on 16".

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Check with member GCMERAK. He's gone through all of this for a bunch of Merak owners and there are threads about it on here. That should help with the 16 vs 17 inch question which is crucial as tire availability disappears daily.

 

Thank you for the advice.
I found this other more recent thread where the issue is discussed with gcmerak
https://www.ferrarichat.com/forum/threads/id-like-to-see-some-meraks.185011/page-33#post-139615645
And also sent him a message

 

I was very lucky to find a set of original BBS RS123-124 and purchased it.
These are period 3pc. 16" forged wheels with the "infamous" 4x130 PCD fabricated by BBS for the Merak and the Bora (see in particular the unique trident emblems instead of the usual BBS one) and they are as rare as hen's teeth, maybe a few sets only fabricated.
The 8" front wheels specs are perfect for the Indy, the 10" width of the rear wheels is however much larger than that of the OEM 7.5"x15" Campy.

The wheels are in as new condition and they are equipped with Michelin Pilot Sport's with full tread depth but unfortunately 12 years old.
Tyres are 225/50 ZR16 and 255/50 SR16 on 8" and 10" wide wheels respectively.

I understand that such rubbers are not really adapted to an Indy, especially because of its leaf springs and live-axle rear suspensions.
Also, even if the rolling perimeter of the rear tyres is close to that of 205/70 R15 XWX (one of the homologated dimensions for the Indy), the front tyres' perimeter is substantially out of specs.
Plus, potential rubbing issues under the rear wheel wells (the 10" wheels having an offset of 30 mm). The 8" front wheels should be OK with the suspensions and steering with a 18 mm offset (standard offset of the Campy's is 21 mm).

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Unless I work out the wheels and replace the tyres, such a set would therefore be only usable for show.
I have two questions:
- for the front, I know that in the past Michelin made the Pilot Sport also in the 225/55 ZR16 dimension (now unavailable, but the combo 225/55 and 255/50 is available with BF Goodrich); would that be more adapted than the 225/50 ZR16?
- for the rear, tirerack does not recommend to put 255/50 tyres on 10" rims, but this was the normal setup for e.g. the Testarossa; would it be better to have a 9" rear rim for a 255/50? Or even come down to 8" rear wheels with the same tyres on front and rear altogether (that would mean rebuilding the wheels with smaller lips and barresl, an undertaking I am not enthusisatic about such rare items...)

 

Bump if I may, wrt to tyre fitment

I have found on this forum that a stretched 255/50 ZR16 tyre on a 10" rim is acceptable as it is the standard fitment on the rear wheels of the Testarossa:
https://www.ferrarichat.com/forum/threads/testarossa-tires-safe-to-run-255-or-not.524364/

255/50 ZR16 and 255/50 ZR16 would also be perfect for Bora's/Merak's which have a central engine.
The OD' of these tyres also correspond quite nicely to the 195/70 ZR15 and 215/70 ZR15 original tyres.

I remain however concerned by the rather small OD and load index of a 225/50 ZR16 tyre on the front of a heavy front engine car like the Indy which has originally 215/70 ZR15 tyres on all four wheels.
Do you think that a 255/55 ZR16 is the minimum required on the front and would be safe enough?

 

I'd make certain that you could fit such tires, what they look like and also a 255 is very wide and tough if you have a manual steering rack, though you coukld also addd in an electric boost unit. Many people have on big, heavy, front engined cars. There's a formula for the calculation of load index as it vaties according to speed. It diminshes appreciably once you get over 120 mph. I don't remember the details but we did check that out for our 160+ open road race run.

It just seems to me that 255 is very wide for up front on a vintage car. Your decision though if it all fits and works. That's the thing about the old original XWX 215/70VR tire. My friend was using these on his Mercedes 6.9 for that race and the next year on his Infiniti Q45. The Michelin engineers told us it was 200 mph tire and not to worry at all about speed or load. It's just a great handling and compliant tire in the twisties. It doesn't or didn't have great break away characteristics but it was a tough GD tire that did very well running straight.

So much has changed since then in the design approach both from an engineering perspective and visual one. The 15" XGT tires in the late 80's and early 90's were fabulous tires but as styles wend more for the Conestoga wagon wheel look and fully exposed brake and suspension hardware in back of ever more complex rims they gave way to much lower profile tires on much bigger rims. The brake hardware has also become incredibly more capable and unless you had LHM brakes that's a very welcomed thing. In the early 1990s a Maserati Bota with those XGTs tires was a wildly better driving sport vehicle than an Indy on 14" rims and XWXs. Both on the road and on the track.

You have a lot of things to consider. The last Indy I drove about 5 years ago was riding on 15" after market wire wheels. They had issues. But worse was that all 4 tires expired from age while I was driving it. They didn't fail completely but the belts were observably separating. I forget the specific size but I was trying to put some Pirelli P4000E 225-65zr15 tires on it as replacements to match the original size. Yet another nice tire that's now gone ... But I couldn't find any. I got something(?) in a HR rated tire and the car drove very nicely through California hills from I5 to Monterey. That's good GT car duty. It was a 4.7 WO LHM.

Good luck and have fun!

This stuff comes up and gets discussed in so many threads, so my apologies for any repetition.

 

Thank you for the very useful comments.

The 255 would go only on the rear and I have still to check on the clearance issue in the wheel well.

Regarding the front, even though my car is a late Indy with power steering, I would certainly put no wider than 225 as 255 would certainly not clear the steering/suspension components.

I will investigate more on the load issue.

 

Looking good

 

Big difference between the 225/50 front and the 255/50 rear:

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The 255 on a 10" rim looks quite stretched:

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In principle a 255/50 should be put on a 7.5"-9" rim so that 10" would be out of range.

Fortunately however, that tire on a 10" rim is standard fitment on the rear wheels of the Testarossa, it seems that the Pilot Sport accepts such a stretching without handling or safety issues:
https://www.ferrarichat.com/forum/threads/testarossa-tires-safe-to-run-255-or-not.524364/

Fitment on the Indy still to be checked...

 

My Indy is not yet back from the restoration in the shop (still works on the clutch, braking and A/C systems) and I didn't have yet the opportunity to address my planned wheels change.
I am however preparing for it.

The original Bora/Merak's Campagnolo wheels are attached to the hubs with studs having a central unthreaded part separating two threaded ends:

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The BBS/RS wheels foreseen for Bora/Merak's have therefore suitable recess holes machined on their back to accomodate the unthreaded part of such studs:

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The design of the studs for other Maserati's of the period is unfortunarely different.
In particular, the threaded ends of the studs for Indy's and Khamsin's are separated by a longer unthreaded central part that cannot be accomodated by the BBS wheels:

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I must therefore extract my current original wheel studs in order to be able to fit BBS/RS wheels:

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And I need to understand how the studs are locked within the wheel hubs.

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Strangely indeed, the diameter of the part of the stud coming out in the back of the hub looks to be bigger than the threaded part of the stud as seen on the other side of the hub (which would render the extraction very difficult) !
Maybe, I hope, a visual artefact...

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Does somebody know how such studs were inserted at the factory?
Is it possible to remove the studs only by unscrewing them with usual stud extractors?
Also is it necessary to locally heat the screwed part with a torch or a heat gun (to weaken possible rust or Loctite in the threads)?

Thanks for possible tips

 

I got the explantion of the attachment of the studs from Fabio Collina.

As I thought, Maserati has used a process to secure the attachment of the studs to the hubs from behind, by crunching the end of the stud so as to widen that end.
Fabio got this info from a friend of his working at the Borrani wheel company:

"The rear threaded part of stud ( the one that goes on the hub flange) has a tapered concave part to create fins to be enlarged by punching with an impact press. In this way a mechanical full locking will be reached. To replace older studs you must grind at rear the caulked terminal part to allow thread to be again unscrew able."

Drawing attached (not the Campagnolo wheel but same principle) to show how it works:

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I think that we, the classic Maserati community, are really lucky to have Fabio around to help us when such detailed technical info is needed. Hats off!