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Vintage Front-Engine V12 Tires

Discussion in 'Vintage (thru 365 GTC4)' started by WillS, Dec 12, 2003.

  1. WillS

    WillS Rookie

    Nov 14, 2003
    31
    Has anyone come up with a good solution for 330 GTC (or any vintage front engine V12) tires of 205-14 ("H" or better speed rating) size? A good starting source of OEM tire size info is Dyke Ridgley's article on the 330 Register website (thankyou Kerry) at: http://www.330register.com/TechTips/Tip_1.cfm

    The aspect ratio that Dyke Ridgley mentions (.82) means that a 205/70-R14 tire will be too small a diameter. A search at tirerack.com by tire size 215/70-14 and H (130mph) or better speed rating yielded only the Firestone Affinity LH30 (All-Season). 225/70-14 only yields SUV tires. 215/75-14 tire size yields 4 tires, all of which only have an S (112mph) speed rating, but these might be the closest to the OEM (e.g., Pirelli Cinturato CN72 205-14) size/diameter. Imho, the 215/70, 225/70, or 215/75 sizes will be closer to the OEM size than the 205/70-14. Tire diameter or revs-per-mile would give an even closer estimate of correct tire size.

    Coker's Michelin XWX 205VR14 is the right size, but not happening at $345 a pop! --and it's old technology anyhow.

    Pirelli has the P4000 Super Touring in 205/70HR14, but this misses by being too small as well. The P4000e isn't made in a 14" size that I could find.

    What have you done about tires for these machines?

    My apologies if this has been covered before and, if so, would somebody please point me to where the discussion was.
     
  2. Dave330gtc

    Dave330gtc Formula Junior

    Mar 12, 2002
    600
    NW Indiana
    Full Name:
    David Smith
    I bought the Coker Michelin XWX 205VR14 for my car. I wanted the original look. I was able to get those tires for about $270 each. They are not on the car yet so I cannot comment on the ride and handling.
     
  3. Bryanp

    Bryanp F1 Rookie
    Silver Subscribed

    Aug 13, 2002
    3,676
    Santa Fe, NM
    I didn't realize you guys had 14" wheels - On the queen, I just got 215/70Z R15 P4000s since I determined that the newest XWX on the car was 13 years old . . .. but that doesn't help you w/ the 14" wheels.

    my father made the following spreadsheet re: tire sizes, but based on a .80 aspect ratio - and for 15" wheels
    width
    aspect ratio
    size
    diameter
    circumference
    % difference
    revolutions/mile

    205 60 15 24.69 77.55 0.13 817.02

    205 65 15 25.49 80.09 3.40 791.15

    205 70 15 26.30 82.62 6.68 766.87


    215 60 15 25.16 79.03 2.04 801.68

    215 65 15 26.00 81.69 5.48 775.58

    215 70 15 26.85 84.35 8.91 751.13



    365 GT 2+2 original spec tires were

    200 80 15 27.6 86.6 730.72
    7.87 in
    estimate for speedometer calibration use 725
    or alternatively

    205 80 15 27.9 87.6 722.87
    8.07 in



    so a tire 215-70-15 looks like this
    215 70 15 26.85 84.35 8.91 751.13
    8.46 in

    not as tall by 3/4 inch and wider by 39/100 inch and speedometer off by
    3.6 %

    Pirelli P4000 Super Touring 215-70 WR 15 specs out at 8.7 section, 26.8
    diameter and 774 rev/mile
     
  4. bill365

    bill365 F1 Rookie

    Nov 3, 2003
    3,319
    Chicago area
    Full Name:
    Bill
    I picked up a set of Avon Cr 39 skins, 225/65/15 for my 365 2+2, they worked out real good, $135.00 @.
     
  5. bill365

    bill365 F1 Rookie

    Nov 3, 2003
    3,319
    Chicago area
    Full Name:
    Bill
    For the 330gtc....
    I did find that Goodrich Radial T/A offers......

    P205/70R14 819.0 revs/mile
    P215/70R14 803.0 revs/mile
    P225/70R14 785.0 revs/mile

    Although they are s rated,

    Cooper Cobra Radial GT offers the following in T rated
    P215/70R14 25.76 diameter
    P225/70R14 26.27 diameter

    Good luck
     
  6. Tony Fuisz

    Tony Fuisz Karting

    Nov 5, 2003
    162
    Bethesda, MD
    Full Name:
    Tony Fuisz
    The biggest problem I think with going with the slightly lower aspect ratio or tire height is the decreased ground clearance-since I know how much the exhaust costs, its all the more painful to hear the occasional scrape on a slightly tall speed bump.
     
  7. oldfart3

    oldfart3 Rookie

    Nov 1, 2003
    10
     
  8. oldfart3

    oldfart3 Rookie

    Nov 1, 2003
    10
    I'm also going to be looking for a newer, more trustworthy set of treads for my Lusso when I finish the restoration in a year or so. I think the 185/15's will be even harder to find than the wider sections.
     
  9. 365boy

    365boy Formula Junior

    Nov 5, 2003
    343
    Brighton, England
    Full Name:
    John Leaman
    Wills,

    Some might say...

    If you want new technology, don't buy a 35 year old car.

    If you want cheap tyres, don't buy a Ferrari.

    You have a fabulous car, and it seems a shame not to have the correct tyres....

    John
     
  10. bill365

    bill365 F1 Rookie

    Nov 3, 2003
    3,319
    Chicago area
    Full Name:
    Bill
    Hi John,

    When I needed tires Coker's XWX's were not available in correct or suitable sizes (they are only available in spurts), the Avons that I got are one of maybe two or three different brands/models that were of suitable size (close eqivalent in height) and Z rated, price was not the issue. They work well (stick, handling, ride, noise), IMHO much improvement over the XWX's that I had replaced. In the case of the 330, there just is not much left on the market to choose from. For concours, of course the XWX's would be favored but for a car that is driven, a modern, readily available tire might be a better idea. Not to say that the Avons were readily available I had to go through a lot of gyrations with Cooper/Avon to allow my local tire shop to order them, even though there were over 200 copies in the Albany, Georgia warehouse. The tires that I mentioned were only for reference, not chosen by price, they were the only suitable sizes available that I have found so far.

    As an added note : Dunlop also has the venerable GT Qualifier in 225/70/14.

    Regards,
    Bill
     
  11. Tspringer

    Tspringer F1 Veteran

    Apr 11, 2002
    6,155
    I appreciate and understand the whole "original" slant when it comes to maintaining an old Ferrari.

    However, I would suggest that tires is one area where going with antique technology for this reason alone is perhaps a tad overboard. Tires such as the XWX are simply horrible when it comes to providing any grip! If you ever find yourself in a panic stop situation.... the difference between running an ancient XWX or running a newer Yokohama or something may end up being the difference between a simple Wheeeeeeeeeew and wipe of the brow or an expensive trip to the body shop!

    Tires are a wear item. Do you make sure you run only original, ancient tech accesory belts? Do you only run 1960s tech oil? How about spark plugs? Do you only run leaded gas?

    My Daytona is very happy running Yokohama AVS intermediates. They are the correct size and do look good on the car. They also provided modern levels of grip and make the car handle light years better than it would on XWXs.

    I do understand the issue with 14" wheels. There are almost NO modern performance tires available in that diameter, so you have extremely limited options. Thats why I bought aftermarket 16" wheels for my '77 308.

    If concours and strict originality is a primary concern.... get a second set of wheels. Run the old XWXs when going to a show.... run the modern rubber when you want to enjoy driving the car!

    Terry
     
  12. WillS

    WillS Rookie

    Nov 14, 2003
    31
    Well John.......I might say....

    You obviously have no idea what my intentions are with my GTC, and to assume you do (i.e., cheap, a shame, etc.) is a bit rude--try being more positive. My intentions are in fact quite the opposite of what your post implies they are.

    The only new technology car out there that revs my engine is the Maranello--but then again you can't work on that one like you can a vintage V12. As that is at least half the fun of Ferrari ownership for me, my 330GTC will do just fine.

    I'm looking for a newer technology, 14 inch tire of the correct size with a high speed rating, and, so far, it looks like a pretty tall order. If I can find such tires, I know they will vastly improve my car's handling over the technology of tires designed in the 60s & 70s. And I will pay for them.

    This is not a show car, it is an unrestored (well, it has a new interior)vintage front engine V12 that will be driven Hard and Fast over some of the finest mountain roads you will find anywhere in the 'States and Canada, and I want the best handling, most MODERN tires I can find for it. Those will be the "correct tyres" for me.

    Regards,
    Will
     
  13. WillS

    WillS Rookie

    Nov 14, 2003
    31
    Bill365,
    Thanks for the tire tips. The 215/225-70 tires look interesting. I'll look in to them further. The missing piece of information we need is what the diameter and/or revs per mile was of the OEM 205/(.82)-14 (e.g., XWX). Does anybody have any idea on that?

    Another way to go is what Tspringer (great post in general! :^) ) says and get 15" rims. I don't think 15" rims will be found in a 32 splined hub size though. Does anybody know if the 365GTC came with 32 hubs and 14" tires too? Another thought--can 330GTC hubs be converted to 42s? Then 15" rims could be used.......

    Pipe Dreamingly Yours,
    WillS
     
  14. Bryanp

    Bryanp F1 Rookie
    Silver Subscribed

    Aug 13, 2002
    3,676
    Santa Fe, NM
    bill - do you get any tire rub at full lock on the wheel well sheet metal w/ the 225s?
     
  15. 365boy

    365boy Formula Junior

    Nov 5, 2003
    343
    Brighton, England
    Full Name:
    John Leaman
    Will,

    Didn't mean to be rude at all. Just the purist in me getting the upper hand I guess.

    Anyhow, good luck...

    John
     
  16. WillS

    WillS Rookie

    Nov 14, 2003
    31
    John,
    No prob,--thanks. Regarding Purism, it would be interesting to ask il Commendatore which tires he would like to see on his street cars--the correct origional tires or modern tires that enhance the performance of his cars. The old purism vs. practicality/performance arguement again, which will never be resolved except by each person for himself.

    Will
     
  17. trevi

    trevi F1 Rookie
    Owner

    May 19, 2003
    2,619
    Switzerland
    i don't know if these tyres do match your search, but you may check the following site http://www.mytyres.co.uk/start.html. they offer 10 different tyres of your preferred dimensions.

    trevi
     
  18. bill365

    bill365 F1 Rookie

    Nov 3, 2003
    3,319
    Chicago area
    Full Name:
    Bill
    Bill365,
    Thanks for the tire tips. The 215/225-70 tires look interesting. I'll look in to them further. The missing piece of information we need is what the diameter and/or revs per mile was of the OEM 205/(.82)-14 (e.g., XWX). Does anybody have any idea on that?

    THEORETICALLY (all mfgr's tend to vary a little) the rolling diameter would be:
    205 x .82 = 168.1mm is the cross sectional height off of the rim
    X 2 = 336.20
    add this to the rim diameter (14 x 25.4 = 355.6)
    336.2 + 355.6 = 691.8
    691.8 / 25.4 = 27.23 inches
    27.23 x pi = 85.565 inches for a circumference
    1 mile = 5320 ft x 12 = 63840
    63840/85.565 = 746.1 revs per mile

    Not that I am arguing with Dyke Ridgely but if the original tire was actually an 80 aspect ratio the overall height gets smaller and the revs per mile goes up:

    328 + 355.6 = 683.6
    683.6 / 25.4 = 26.91
    26.913 x Pi = 84.55
    63840/84.55 = 755.05 revs per mile

    approximately a 1.2 % difference

    The Goodrich 225/70/14 with an rpm of 785 compared to the first case, represents an approximate speedo error of 5.21 % and a change in car height of about 1/2" versus the 82 aspect ratio.

    When the Goodrich is compared to the second case there is an error of 3.96%.

    The question about the 15" rims on 32mm hubs, I believe that the only standard (if you want to call it that) available rims (15"x32mm hub) was the 275 competition wheels (read $$$ add hard to find).
    Other solutions for 15" wheels could include:

    If you have wires, find a set of 32mm hubs and have them strung onto 7x15" rims.

    Or... If you have alloys use your wheel centers and have the wheel manufacturer of your choice machine/drill their wheel centers to fit/match your hubs.

    If you happen to get any deeper into the wheel issue, about the only thing I can suggest is that you call Tom Shaughnessy - 949-366-6211.

    Regards,
    Bill
     
  19. Slim

    Slim Formula 3

    Oct 11, 2001
    1,735
    Pacifica, CA, USA
    Full Name:
    richard
    Just a heads up - the Pirelli P4000 super touring are terrible. I had them in 205/70/14 on the dino coupe and man, those things squeal like crazy and don't have much grip either. It was mostly the sound that drove me crazy though. I'd avoid them.

    Going with modern larger wheels and modern tires is fine for some people, but you need to keep an eye on suspension components because you are changing the dynamics of the car by running heavier wheels and tires with less sidewall, etc. You may find that parts wear faster than with the original tire and wheel size.
     
  20. WillS

    WillS Rookie

    Nov 14, 2003
    31
    Yeh, I've been doing the same calcs for tires and agree, except that 1 mile = 5280 ft., so the 205/82-14 is 740.5 revs/mile and 205/80-14 is 749.4 revs/mile. I came across an interesting refinement of the calcs at:

    http://tigersunited.com/tech_tips/Rhoades-Speedo/rt-Rhoades-Speedo15.asp.

    Thus when the tire is loaded, the circumference shrinks by 3.1%, and the revs/mile under running conditions are 3.1% higher. So, underway (loaded), a 205/82-14 would turn at 763.5 revs/mile, the 205/80-14 tire would turn at 772.6 revs/mile, and the 225/70-14 runs loaded at 787.6 revs/mile. So I get a 1.9% difference (772.6 vs. 787.6)--pretty small. Hope I got those calcs right.

    Example calc for 205/80-14: 205(2)(.8)/25.4 + 14 = 26.913 dia. 5280x12/(pi x 26.913) = 749.37 revs/mile (unloaded). 749.37 x 1.031 = 772.6 revs/mile (loaded). 787.6/772.6 = 1.019 or 1.9% difference.

    That 0.5" lower won't help with speed bumps very much, and I'll have to watch the full lock wheel rubbing.....should be an awesome increase in handling though......:). BTW, do your (are they?) 225/70-15s rub at full lock? What Ferrari do you have?

    It'd be great if you're right about this, as it brings the 225/70-14 closer to the OEM specs than does the 205/82 tire. The thing we need to know is what an accurate circumference is for a mounted, correct pressure 205/(82 or 80)-14 OEM tire. Then we can run the numbers backwards and answer that question. I'll see if Dave330gtc has mounted his XWXs yet.

    How do you arrive at the speedo errors?

    My set of Borrani wires will eventually have XWXs on them to show with, so those'll stay the same. I'm blessed to also have a set of 10-hole Campy alloys with splined 32 hubs, but I don't follow what you're saying about "use your wheel centers........machine/drill their wheel centers"--please elaborate? Are some alloys bolt-mounted, not spline-mounted?

    I've heard a lot about him--hope he can help. I'll talk to him.

    Thanks much for the great input!

    Regards,
    Will
     
  21. bill365

    bill365 F1 Rookie

    Nov 3, 2003
    3,319
    Chicago area
    Full Name:
    Bill
    Hi Will,

    "How do you arrive at the speedo errors?"

    The errors that I calc'd was simply the revs per mile of the theoretic 205/82 tire in comparison to the 225/70 rpm's.

    "Campy alloys with splined 32 hubs"

    As a possibility, not that I have researched it at all, if you have the bolt in splined wheel centers, you could unbolt them from the rest of your wheel and have the wheels of your choice (of course with a matched offset) before they are drilled in their normal lug bolt configurations, machined and drilled to fit the Campy wheel centers, VOILA.

    BTW, do your (are they?) 225/70-15s rub at full lock?

    I have 225/65/15 and no they don't rub, but I have a 365 2+2, I believe that 205/80/15's were standard.

    If you go to 15's you would use a +1 configuration, a lower profile performance tire to match the height/rpm of your 14's. Plus one means when fitting a 15" wheel you would add 10mm to the original tire width, subtract 10 from the aspect ratio and have a 15" rim size, (205/70/14 plus 1 would be 215/60/15). Or.....add 20 to the original width, subtract 15 from the aspect ratio (205/70/14 = 225/55/15). 235/50/15 etc.

    Regards,
    Bill
     
  22. parkerfe

    parkerfe F1 World Champ

    Sep 4, 2001
    12,887
    Cumming, Georgia
    Full Name:
    Franklin E. Parker
    That $345 price from Coker seems pretty good to me. After all, its a vintage tire for a vintage Ferrari that was very rare. Once you buy a set you probably won't need to replace them for a decade or so. And, it is my understanding that Michelin uses modern rubber compounds in the vintage tire they make. Again, if you can't afford tp maintain a Ferrari in OEM condition, then you can't afford to own a Ferrari.
     
  23. bill365

    bill365 F1 Rookie

    Nov 3, 2003
    3,319
    Chicago area
    Full Name:
    Bill
    Hi Franklin,

    Maybe you should read the whole thread, the issue is NOT price. The main concern is that the Michelin XWX's do not, in many peoples opinion, have the sophistication of traction, handling and ride characteristics that they desire for serious driving, include me in this group.
    It also seems that Will is considering spending MORE money in finding an acceptable solution to what he percieves as a problem than it would cost to simply buy the XWX's from Coker. I am, in my limited capabilities, attempting to assist him in finding a solution.
    I can appreciate the XWX'x as being proper for serious concours competition and I surely have nothing against Corky, but for driving a Ferrari in a spirited fashion there are better tires out there than XWX's. Will's problem is that he is trying to find modern performance tires that will fit in his wheel wells, even though it may mean acquiring a set of 15" wheels/tires for driving. Many F-car owners have two different sets of wheels and tires, one set for showing and another set for driving, I for one, do not see a problem in this. Are you saying that you do?

    Regards,
    Bill
     
  24. bill365

    bill365 F1 Rookie

    Nov 3, 2003
    3,319
    Chicago area
    Full Name:
    Bill
    Franklin, as you may be able to tell from the little icon picture next to my name, I had XWX's on my 365 before changing them.
     
  25. Bob Zambelli

    Bob Zambelli F1 Rookie
    Silver Subscribed

    Nov 3, 2003
    2,638
    Manning, SC
    Full Name:
    Robert G. Zambelli
    I have been driving a 1967 330 GTC since 1975 and, having put over 110,000 miles on it, I can claim reasonable experience.
    I’ve used the following tires: Pirelli (CN-72 as I recall), Michelin XWX, Goodyear Eagle GT, B.F. Goodrich Comp T/A, Yokahama Y(???)VR, and finally Pirelli P-4000. Since I had my own tire changing equipment, I could experiment as I wished.
    When running tech and instructing at FCA track events in the 70’s and 80’s, I spent a considerable amount of time on the track, pushing the GTC to its limits. The absolute best all around tire I used, both for track and road was the Comp T/A – 205 or 215/70 VR 14 – I can’t recall the size, but I do recall that although it worked well, it did not last long. (I also used the Comp T/A on my 308 GT/4 and they were fantastic). The CN-72 was ok but the XWX was the worst tire I ever put on the car. The best road tire, as well as the longest lasting was the Yokahama.
    Although I no longer participate in track events, I still use the GTC as an everyday car and drive it aggressively. It has around 160,000 miles on it now and it’s working quite well with the Pirelli P-4000. They are 205/70HR-14 and I have never bottomed the car. Since it’s equipped with Borannis, I must run inner tubes. I keep around 35 PSI in the front and 36 to 38 in the rear and I have yet to have them let go when cornering hard. Wear seems pretty reasonably but time will tell. They perform reasonably in the rain but I’ve never driven it in snow so I can’t comment there.
    For what it’s worth.
    Bob Zambelli
     

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