Dr L-88

Even though I initially posted this in the C3 section, I'm sure there are some guys who hang out in the C2 section who can answer my questions too....................

I am looking for information from you guys who "were there, back in the day", when Corvette began to rule SCCA racing.......1968 - 69 - 70 -.......

In particular I'm interested in the size wheels (15 x ??? width) and the tire sizes used on the 68 and 69 "NON FLARED" Corvettes.

The first two cars that come to mind are the Garner A I R cars and the Sunray DX cars, but I'm sure there were others. Anyone who was there and knows for sure what size wheels and tires would have been used, I would appreciate hearing from you.

Thanks in advance for your input.

Rex

63Corvette

Well......I ran, and won with 8"X15". Others may differ

Dr L-88

Thanks Garrett............................nice looking car. What size tires did you use on the 15 x 8 rally wheels?
Thanks,
Rex

TCracingCA

Too much attitude when you try to give tech info to help a guy from the Know it alls! Thus I like the type of topics that you put up. They are more to my interest.

Basically I do have all of the Competition guidelines for the first years of IMSA and the SCCA Competition guides.

So it depends on which racing series you want to talk about. GTO would be an IMSA class and gave Corvettes some place other than the SCCA production class to run. Then later SCCA countered by allowing Corvettes into there top class of Trans Am. Thus SCCA was generally an 1-1/2 over stock on the rims. No real restrictions thou on the tires, except what was available back in the day caused the restriction in what was run. The IMSA got pretty liberal on the rim sizes by 1974. Not many thought of flaring to the extreme prior to 1974. The Trans Am did have tire size restrictions. I also when I get a chance pull out the specific IMSA early rules and see what they wrote as for rules on the 1971-1973 seasons. Porsche was the manufacture cheating, and led the flare wars. The organizers allowed the Corvette to compete by letting them get flared. The early IMSA was run mostly to Homoglation (FIA) and then became less restricted. Porsche produced the minimum cars and they were flared, so allowed to race (RS and then RSR). Then you had the Turbo 934's and they were at first restricted to not upset the RS and RSR owners. Thus no one cared about the Corvettes and they usually except for a few became uncompetitive. Thus AAGT specs and Dekon Monza's etc. Then the 935 was restricted similar to the Turbo 934. Thus a hybrid 34/5 came out to skirt the rules. Thus in a quick reply to a forum, I have to write this loosely but it gets the point across as to what was happening.

Scca held to close to production spec until about 1972 and then were losing contestants to the money paying races of IMSA. So in the early years of IMSA, they were pretty much SCCA racers and to that spec because guys competed in both series and would go back and run. But that quickly changed and flares were allowed. Thus in 1973 flares were the norm. Some of it started in 1972. Also American Racing had the 10 inch rims and at first it was not allowed 1969/70 in SCCA, but was accepted around that time because it was close enough to the 9-1/2 rule. I am writing this all from total bad memory. I do have the notes somewhere for precisely what was allowed, but it is not fun to dig it all out and waste an evening unless really necessary.

66since71

Built my C-3 (15x10s) after the flare rules.. But... I also recall the SCCA pre-flare, +1.5" rule. I'm certain that true mags were available for C-2s in 15x7.5", 0 offset. With the right tires, they cleared stock fenders, with lips shaved. Required trailing arm mods and shortend main leafs. I'd be surprised if 15x9.5" wheels were not also available for C-3s, similarly modified.

Interesting thread..

Harry

Edit, Guldstrand sold the wheels. Someone there may remember.?

63Corvette

The rear tires are Goodyear 11X27, and the front tires are 10X25 or 26 I believe. Initially I couldn't afford the stock GM part number flares, so I ran front tires all the way around. Later I got the flares, the bigger tires, and cheap mag wheels. The fast (sponsered) guys ran Jongbloed wheels or Minilites. BBS 3 piece wheels were just coming into fashion.

TCracingCA

The start of Imsa was 1969 and into 1970 they started with Formula classes and a Sedan rule that was basically a 1 inch rule. I have it if someone has a Sedan and is really interested, I didn't didn't feel like typing it.

1971 The IMSA allowed entry of Corvettes and the FIA rules that applied were Group 2 initially. Later Group 4, and then it evolved into Group 5 rules and regulations. But the initial was Group 2 and that is why Porsche showed up.

Basically everyone Manufacturers marketed a 10 inch (Cragar, American) so the 10 inch bent the rules just a 1/2 inch and were allowed. Thus the 10 inch is the rule originated 9.5 for the SCCA basically, but the IMSA was FIA class based! I have a set of SCCA proper widened stock Rally rims built to the 9.5 rule in my garage that was enforced in most jurisdictions (not all) in and around 1970. When ImSA and 1971 came. SCCA allowed the rules bent, and the American 10 inchers popped up on cars. Also both organizations want bragging rights to the faster cars. Thus a rim width rule within reason developed and then IMSA went Group 4 and then the SCCA countered with Trans Am allowing wider!

The SCCA was a bunch of D!(KS back then when Tracy Bird showed up. They would penalize members that ran IMSA events. To counter, the Imsa put the main office a few miles fromt the SCCA headquarters. And did a bunch of crazy things to attract competitior and I actually kind of buy into the Cuba story related to flares. They let the Cubans run their liberal body modifications to fill the fields down in the Floridas etc.. Also because of the FIA Group 2 rules, they knew that European entries would be attracted and that this would further fill the fields. Thus essentially they had created a Series to compete internationally which did not exist in Road Racing for production class cars. Then with these kind of rules allowing for a wider range of entries. Porsche recognized the exposure and basically was turning out turn key race cars from the factory with full support. There was quite an imbalance and the independants like Greenwood, Mo Carters, Sloma, etc. had to field real interestingly engineered cars. Thus cost evidently got out of control and with factory backing, they eventually went back to Homologation rules in and around the 1982/3 seasons. Thus eventual a Corvette in IMSA around 1984 was down to one or maybe two (Dingman). GM would not develop Homologated racers like BMW, Porsche, Mazda etc. were doing. But they went after the big title with the intro of the GTP Corvettes.

SCCA because of funding from membership fees had limited money and thus would drop car types that didn't regularly compete or not quickly write rules to allow a new car type. But IMSA would take anyone and anything. SCCA tried to maintain an amateur place to play and their Trans Am was there Pro Series.

I collect notes on weird car stuff. I could put together a point by point history but it would take time. Plus I would want to be published and paid!

gbvette62

I agree that up until 72, the SCCA wheel rule was stock width, plus 1.5".

From what I remember of the SCCA rules for tires, they were only limited by: 1) the sizes commercially available at the time, 2) any size that fit safely on the legal width rim, and 3) they had to fit within the stock fender opening. Fender widening was allowed in some classes (such as Trans-Am), but the stock wheel opening had to remain unchanged. Full on flares were not allowed prior to the early 70's.

All of this changed in 73, as a result of competition from IMSA, as TCraningCA said.

To get a good idea of the pre-72 SCCA rules, check the SVRA's website for their rules, as they're basically the same as the pre-72, SCCA General Competition Rules (GCR). The SVRA has allowed some variations from the original SCCA GCR (mainly for safety, reliability and parts availability), and those variations are noted in their rules.

The SVRA rules specify 15 x 7.5 (stock 15x6 width, plus 1.5) wheels on mid year Corvettes, but allow the use of Torque Thrust D's in 15x8.5. For 68-82 Corvettes, the rules are similar in that the specified wheel size is 15x9.5, but 15x10 Torque Thrust D's are acceptable.

Dr L-88

Thanks for all the information everybody. It's most imformative.
Now can anyone tell me what size wheel / tire combo the Sunray DX car and the Garner A I R cars used? These cares were not flared.
Thanks,
Rex

Yenko Sunray DX 68 L-88



One of the 3 AIR L-88s campaigned by James Garner's team

gbvette62

I can't say for sure, but I'd guess that they are probably no larger than 15x8's.

The DX and Garner L-88's were 68's, so initially they would have been limited to a 15x8.5 wheel (68's came with 15x7" rims). I don't know that American was making wheels in half inch widths, at the time, so I'd guess that they were 8 inchers. They don't look very wide, as the is no outside depth (or offset) to them at all. They might even be 7 inch wide.

If I get a chance, I'll look through some of my old Corvette News Magazines, from the late 60's. Chevrolet often included articles on Corvette road racers and how they were prepped, back then.

TCracingCA

I thought I answered the question close enough. Ok

1968 FIA 7" rim, no flares, 1969 8" and flares, 1971 FIA/IMSA allowed Group 2 flares and the rims/tire sizes went up to 10 inch.
1968 SCCA 1.5 rule or 2 inch rules on the track width basically whichever was bigger. Thus Corvettes stayed 1.5 over. SCCA at the beginning of 1972 no flares and then by mid 72 to the end alot of homemade to the limit of the tire, and definitely 1973 SCCA got flares and usually the Factory or Group 2 units. In 1972 SCCA the widened rule went to covering the wheels, so lips and things were used, but flares in the traditional sense no at the beginning.The basic 1.5 rule still was in effect in 1972 SCCA
Thus the #44/#45 cars ran in FIA initially at the Daytonas and Sebrings and then Cormany family bought the car for 1972 and ran SCCA basically. Then you had the in between. Thus during these transition years, sometimes the Cars like in 1971 were flared for Group 2 and 10 inch but to put the car in SCCA, they had to run 1968 8.5 rims which looked funny , and then 1969-72 they had to run to 9.5, but by 1972 some slack was given to 10 inch because of the IMSA challenge and the stealing of competitors. Thus with the 8.5 rims and the 9.5's, sometimes you see a car not flared and the wheels stick out with the 8.5's, and stuck out alot more with the 9.5's. Inn 1969/70 most guys in SCCA fixed that with lips, but the car from the side had to retain the basic stock wheelwells. ImSA was FIA so cars with lips over the tires then could run wider rims to 10 inch and thus now the tires suck out again unless flared to 10 inch. The only thing that I haven't looked up is the implementation of Group 2 and when FIA got to flare. I will look that up now! OK I have it, 1969 which coincides with Duntov and the ZL-1 testing and factory flares. The late races 1968, the Owen Corning team basically enlarged the wheel wells, because they were more SCCA based cars so they couldn't. But by 1969 Daytona they were flared on the FIA cars, but not for the SCCA races later. Thus without checking the precise VIN numbers. I do believe they ran the two premiere events Daytona and Sebring FIA in 1969 with flares allowed, then cut them off when they got into their SCCA season. But then would put them back on for like Watkins Glen which was FIA, and then back to no flares for the ARRC and SCCA later events.

The cheat was Greder at LeMans in 1968 and team. His car was flared, and they got away with it because they were French. On the homefront, The 1968 Air cars were running 7 inch tires, but then with the Homolagtion paper submission of the 1969 model, they jumped to 8 inch before the 1968 season was over and they basically ran the biggest rubber that they could fit. Thus the tires look oversized in stock wheel wells. Basically the very first set of 1969 model year rally wheels were sent to them, so they got them pretty early and thus had the argument of stock! But in the prep pics of the AIR team you see American's, but then they ran the Rally's initially in the FIA events, because the Americans weren't initially permitted or thought to be (homogolation). But the DX team showed up with some Ansens and Americans, but the rationnal was that the tire rubber was the same. Thus AIR bascially got their butts kicked. In SCCA at the ARRC runoffs at the end of 1968, everyone was on 8.5's Americans and no flares per se! So the rubber protruded out. But the AIR showed up with "my" 9.5 modified rally's and tried to cheat (but to the letter of the rules by literally having exactly +1.5) a little even though they had more weight. And I own those rims (I don't know if they were the only set made to this exact spec?). I own the Cormany C2 car and the AIR C3 car was sold to Cormany. Because the 10 inch Americans came along, I don't think too many others if any rally's got welded back then. Also I have some of the Lotus rims that came off of Guldstrands Can Am car, that was from the wrecked ex Jimmy Clark Lotus. Basically this all was acquired when Guldstrand was cleaning out, after the end of the AIR team program and the selling of the cars. Thus in 1972 by the Runoffs, they (most cars) ran the Americans and flares or Cragars etc..

Thus because I just typed alot and fast, without precise notes mostly from my memory---- don't beat me up if I got one little thing wrong. I am sure I could get the chain of tire/rim combos perfect, if I wanted to spend the entire night proofing the exact happenings for each race, thus it isn't going to happen. Do it yourself!!!!!

Thus get the point! Not easy to summarize because you had three racing organizations merging during the same period of time

keystonefarm

Rex I would almost guarantee those are 7''. Take a look at the pictures I sent you. The picture of my 66 in white has 7'' wide Americans in front and 8'' wide at rear. The picture of my yellow 66 taken back in Sept 1968 has 7'' wide front and rear as that car was never flared. Using some old memory here but i believe that American offered wheels in 6'' 7'' and 8'' back then. ---------- Ken