1965 gt350r prototype development unidentified tire

[SeanSide]

Hi everyone,

I found these old pictures that seem to be of shelby & ken miles developing the GT350R in 1964-1965. I noticed the tires appear VERY small compared to what is installed on even the real perfectly restored cars that sold millions at auctions. They clearly read "Goodyear" on the sidewall. But my question is:
– Does anyone know the model and exact tire size of these mysterious tires?

These are not like the "goodyear blue streaks sport car special" 6.00-15 tires sold today.

On an other forum, i saw Fred Hilbert the owner of SFM5R094, mention they used to run "Goodyear Blue Streak Sports Car Special. Size Front 5.25x9.50x15 and Rear 6.00x10x15".
(Tire size nomenclature is weird but i think it means: section height / section width - rim diameter)

So i assume:
5.25+5.25+15"rim = 25.5" overall diameter
9.50 = sidewall to sidewall width
6.00+6.00+15"rim = 27" overall diameter
10.00 = sidewall to sidewall width

Maybe the size of the prototype development is the "5.25x9.50-15" on all four corners. But after finding pictures of those exact tires, the tread is not the same as the black & white pictures of the prototype tires, and prototype tires still look smaller.

I want to put small tires on my project gt350r to replicate the same silhouette and went down the rabbit hole of trying to find information about the very first tires used on these cars to find something currently available with the closest final dimensions.

Any input is welcome.

Thank you!

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[SeanSide]

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[SeanSide]

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[CSX4781]

Well, that diamond tread is the same as a pair of 8.00/8.20-15 GoodYear Stock Car Specials I have, although those in the pictures are definitely smaller than mine (although the radiused rear fenderwells make those tires in the photos look smaller than they are; notice how they fill the fender opening on the front). I think the diamond tread pattern was changed to more if a 'hash' pattern on the stock car specials around 1965 (I have a bunch of those too for an unfinished stock car project). The GoodYear Sports Car Specials in that period have a pattern similar to the late 60s GoodYear stock car tires. I have a set of tires for my 66 GT350 (on magnesium R-Model wheels that fit well; 5.50/9.20-15 rear and 5.00/8.30-15 on the front). The fronts are a perfect fit but would be too small for the rear. Hope this helps.

Dave

[98SVT - was 06GT]

002 was the prototype Competition Model. It got the large rear wheel openings. The SCCA didn't like them so the rest were smaller. The 3rd car built 001 was the first "production" car and all others matched its configuration. 002 is the only one of the 3 with the serial number in the proper sequence. The first car built was the street car and was the PR car. When they finally put tags on them it got 003.
CS was the SoCal Goodyear race tire dealer so he had access to the whole catalog and probably an ear or two in Akron to build what he wanted.
Jim Murietta did the wheel wells on the R Models. You might contact him at OVC (Original Venice Crew) to see what he remembers about the tires he was probably given and told to make them fit. Those small tires may have been used while they were trying the IRS in the Falcon.
Since SA sold the Gardena building Jim has moved OVC to Huntington Beach near Foose's. He's also making a lot of the unique R Model parts. Much of it on the original tooling.
I like the shot with the reverse scoop that Pete Brock had planned. Ford ran it past their engineers at Ford Aerospace and they nixed the idea.

[SeanSide]

Amazing info Dave! thanks a lot for those new sizes, i never saw them listed anywhere, and they do look to fit perfectly on your car. I agree with you that the fronts look like they fill up the fender a lot better on the pictures. Also agree that it seems like there was a tread patern change in that time period as I can't find any pictures of the same "diamond" tread anywhere.

[SeanSide]

98SVT WOAH! I'm so happy i asked that question, mind blowing history! I had to read it a few times to piece it all together 😂

Great idea contacting the guy who had to stare at them for hours to bend the fenders to fit (Jim Murietta). I heard him mention he did the fender flares on these cars in many videos & interviews, never thought asking him about the tires.

Outstanding info already, thanks a lot. I will try to reach Jim and report back.

[Dan Case]

BLUE STREAK STOCK CAR SPECIAL 6.50/6.70-15 tires were common as front tires in Shelby team race Cobras on and used by SFMR002 during the track session covered by Sports Car Graphic. The left rear wheel on the car in one picture was an American Racing drag race wheel for Cobras with the spline drive adapter and hat removed but retaining the chromium plated lug nuts left from the Cobra assembly. I reverse engineered the lug nuts and captured washers into drawings for the car's owner so he knew what to look for.)

I kept a some of the research material from helping with details of SFM5R002's restoration. SFM5R002 had quite a few parts from the Cobra department that track day including a 1964 type five bolt HP289 4V race engine and experimental Holley Custom Shop 1964 made prototype R-3259 700 c.f.m. carburetor.  Several of us identified components in picture previously published and not published and helped come up with all the period and or Cobra roadster parts required. The mechanical tachometer drive and cable, also like 427 Cobra CSX3002 used early, were adapted from a tractor application and new old stock parts were tough to find.  (SFM5S003 had an oil pressure gauge form a engine powered lift truck like Shelby American used. It took me a long time to figure out which exact model of lift truck and which exact model of oil pressure gauge was required. After that, I found a gauge for the owner to buy in a few days.)

Side Bar: Shelby American had access to every type of tire Goodyear Tire and Rubber Company made and used models made in England and the U.S.A.  The size, type, and rubber compounds they chose for a car, driver, or event could be anything in stock that the rules allowed sizes of wheels wise.

[98SVT - was 06GT]

.....used by SFMR002 during the track session covered by Sports Car Graphic.

Jerry Titus was sent to cover the test. CS asked him if he'd like to do a few laps. Within a couple laps he was running within a second of Miles. CS offered him the ride and the rest is history. Titus had know CS from his NY days while he was working at Bill Frick Motors (Studillac). CS brought his bent Maserati in. He'd been told it was unrepairable. Titus fixed it and the rest is history. 

[silverton_ford]

98SVT WOAH! I'm so happy i asked that question, mind blowing history! I had to read it a few times to piece it all together 😂

Great idea contacting the guy who had to stare at them for hours to bend the fenders to fit (Jim Murietta). I heard him mention he did the fender flares on these cars in many videos & interviews, never thought asking him about the tires.

Outstanding info already, thanks a lot. I will try to reach Jim and report back.

Bernie Kretzschmar is the one you should really talk to about how the R-Models were built.

[roddster]

  The backward hood scoop: Yeah, testing proved that the car was faster that way, but, seems it was nixed as one of those "we've always done it this way" things.

[pbf777]

The backward hood scoop: Yeah, testing proved that the car was faster that way,

    Not disputing this, but if so, did "testing" (do we actually have any documentation?) absolutely establish why?   

    Scott.

[kram350]

Did not Jerry Swartz do the R model rear re-radius mods?

[98SVT - was 06GT]

Did not Jerry Swartz do the R model rear re-radius mods?

On the production cars. To these specs. Anybody ever come across a set of fiberglass R Model fenders?

[98SVT - was 06GT]

The backward hood scoop: Yeah, testing proved that the car was faster that way,

    Not disputing this, but if so, did "testing" (do we actually have any documentation?) absolutely establish why?   

    Scott.

I have a copy of the Ford Aeronautics report somewhere (it is online.....somewhere). I don't think any "real" testing occurred beyond what Brock knew would work. Here is a link to the hood Brock designed for the OVC car - https://www.saac.com/forum/index.php?topic=23209.msg175351#msg175351  I was at Willow when they tested a second one without the extra vents. They tufted the hood and filmed it with a drone - it worked as Brock predicted.