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I have Coker Gold Lines on my '66. I have never really noticed a significant flat spotting issue. A friend tried some Kelsey Red Lines on his '67. He reported that those tires flat spotted terribly, and there were times he drove and drove and drove and they would not stop the bouncing (yes, he had them re-balanced, etc. and was told it was probably the tire construction). He returned the tires. Anyone out there ever hear that one brand vs another may have more issues of this type? Also, would the mid-year type of tire flat spot more than a '69 repro of the Goodyears (were the later tires belted in place of regular bias construction)?
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Re: Repro Tire Question
Everett-----
Regarding the 1966 tires, were both sets of tires the same cord material? I believe that nylon cord tires are more susceptible to flat spotting than rayon cord, or vice-versa. Also, lokk for an "NF" designation on the tires. This designation means "non-flat spotting". Many early tires were not so-rated.
As far as the 69 tires go, the most authentic reproduction available today is the Goodyear Speedway Wide Tread available from Kelsey. This is a bias belted tire, as original. The Firestone Wide Ovals available today from Coker are not the exact tires used on Corvettes of the period. These tires are fiberglass belted, not bias belted as were the original Firestone Wide Ovals used on Corvettes. They are a better performing tire, though.
Most, if not all, of the Goodyear Speedway Wide Treads available from Kelsey are "NF" ratedIn Appreciation of John Hinckley -
Re: Repro Tire Question
Thanks for the info Joe. I believe the Coker is 4 ply polyester, and the Kelsey is 2 ply nylon. Maybe the 2 ply nylon is more prone to flat spotting. As far as the '69 tires go, I am on the verge of ordering a set of the Kelsey NF F70 Goodyear tires. Hopefully they will round out in a short driving distance.Comment
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Nylon cord tires
Nylon was traditionally the stongest and most heat resistant cord around, but it does flatspot, though the flatspots from sitting should work out with a few miles of driving as the tires warm. The flatspotting should not be permanent. Flatspotting applies to both bias ply nylon cord tires and speed rated radials with nylon stabilization belts. RPO P91 for midyears was a blackwall nylon cord tire, which probably offered better high speed capability, but few were ordered.
To check if you tires are actually out of round, drive it for about thirty minutes to warm the tires, and when you park it back in the garage jack up the front, spin the tires and eyeball for out of round. They should be no more than about .030" - about a spark plugs gaps worth. If they are more, the tires should be considered defective due to out of round.
DukeComment
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Square tires
Even the modern radials produced today are somewhat out of round. On my last several cars (a 300zx, MR-2, and now a porsche 944) I've had to have the tires "trued" to make the tire and wheel combination perfectly round and smooth out the ride. The shop that does this for me tells me that it is perfectly normal, and not a defect. I think its way too expensive ($90 to true and balance all four wheels) for it to be normal, but it's happenend to me on five or six sets of tires of different brands. I always break down and have it done just so my teeth arent vibrating out of my mouth at 75 mph.Comment
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Re: Square tires
Whenever I have tires mounted and balanced, I always eyeball across the tire while its spinning on the off the car balancing machine to see if it's round. Most cars will handle up to about .030", but cars like 911s and MR2s which have very sensitive steering a lightly loaded from ends will not tolerate that much. C2'C3 Corvettes are pretty sensitive too. Out of round can make the steering wheel shake, which is the same symptom as static out of balance. Dynamic out of balance will cause the wheel to wiggle back and forth. My experience is that higher speed rated tires are generally dimensionally more accurate than non-speed rated tires.
DukeComment
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Re: Repro Tire Question
Is either tire more desirable for judging purposes?Comment
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Re: Repro Tire Question
Actually, yes. At least for mid-year cars, the Kelsey tire script on the sidewall gives the load range in lbs, instead of saying load range B which did not come about until several years later. Both tires do have DOT markings, by law, but I have heard "rumors" that guys have actually removed the DOT letters... of course no NCRS member would ever knowingly mislead a judge. Anyway, the Kelsey tire can be made to look almost exactly like original mid-year tires.Comment
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Re: Repro Tire Question
How about for my '69?Comment
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MIchelin tires cure all ills....
...even though I prefer Goodyears in most instances, I find that I have never even had to put a wheel weight on a Michelin, much less have one trued. If your car is sensitive to tire imperfections and Michelin makes a tire of your configuration, go see Bib.
JPComment
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Re: MIchelin tires cure all ills....
i agree with jeff that michelin tires will cure most tire related problems, they are the best you can buy and they wear like iron and still have good traction because they are siped the full depth of the tread not half way like most tires.Comment
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Re: MIchelin tires cure all ills....
I had balance problems for most of the 47,000 thousand miles I ran Michelin X radials on my SWC from '64 to '68.
DukeComment
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Re: MIchelin tires cure all ills....
duke you must be older than me, i never used michelins till the 80s and i found that they took less lead than the tires i took of the car.Comment
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Well, maybe...
I skipped K through six and got my driver's license at age 7, but knocked off ten years in the late sixties so I could be part of THE MOVEMENT. I think Varooom has been around longer than both you and me put together:)
D...Comment
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Re: Repro Tire Question
The only Coker tires I have experience with are for my mid-year, but I am about to order a set of the Kelsey F70 tires for my '69 b/c the car came with Goodyears, and Kelsey is the licensed Goodyear repro manufacturer. Their tires look great and are almost perfect copies of the originals. Someone here probably knows something about the molds they use - maybe they are the originals?Comment
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