Correct Tires

[Paul A.]

[Don H.]

Re: Correct Tires

Paul, I personally think bias ply tires are dangerous if driven very much. Radials completely change the car's drivability. That said the ideal situation is to have a set of both if the car is being judged but the decision is up to you. Good luck, Don H.

[Mark F.]

Re: Correct Tires

Paul, I personally think bias ply tires are dangerous if driven very much. Radials completely change the car's drivability. That said the ideal situation is to have a set of both if the car is being judged but the decision is up to you. Good luck, Don H.

Paul,

I completely agree with Don about handling on bias ply tires and having two sets of wheels (judged ones and driver ones).
I drove my car on then-new Kelsey bias plies to 2 Regionals (2001 and 2003) and the National in Carlisle (2003).
I don't have a trailer and didn't want to go thru the hassle of switching out rubber at the Meet

My wife followed me in her car (we needed alternate transportation while out there) and as we traversed the PA turnpike from Pittsburgh to Carlisle (~200+ miles) she said she couldn't believe how much the car was weaving left and right all over my lane in front of her...handling was horrible compared to radials. Hold the steering wheel straight and the troughs in the hot asphalt made it like wagon wheel ruts on a dirt road.

I suggest (as Don has as well) - keep your radials - buy a second set of correct wheels (or mount the new tires on your correct wheels and get replacement wheels for the radials).

Yeah, it's a fair amount of money, but you'll hate driving your car if you sell your radials and expect to only have bias plies to drive on...just my 2 cents worth...good luck !

[Russ S.]

Re: Correct Tires

From what I have been told radials and bias ply require a different set of alignment specs in order to handle well.

[Paul A.]

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[Kenneth B.]

Re: Correct Tires

Paul, I personally think bias ply tires are dangerous if driven very much. Radials completely change the car's drivability. That said the ideal situation is to have a set of both if the car is being judged but the decision is up to you. Good luck, Don H.

We drove on them for many a year with no problems. They just drive different.

[Garry B.]

Re: Correct Tires

Paul, I would keep your eyes open for a set of nice Bias ply gold lines on Facebook, flea bay or other on-line sources. Many guys purchase a set of both, one for driving and one for judging. The judging tires usually end up in the way once you are done with judging and you see them come up for sale pretty frequently. I was able to find an almost brand new set of 5 bias ply's for my '67 for $200 and used them for my Bloomington Gold judging two months ago. I will also use them for NCRS judging coming up and when I am done I will look to pass them on to the next needy Corvette owner. They are older than what I would want to drive around on, but great for judging. You will however also receive a standard deduction for the reproduction bias ply tires, but not as much as your radials.

[Don H.]

Re: Correct Tires

We drove on them for many a year with no problems. They just drive different.

That is very true. The problem is everyone is used to radials now and may not be prepared for the "quirks" you get with bias plys.

[Michael H.]

Re: Correct Tires

I had my 67 set up ( 4 wheel alignment ) for bias belted Kelsey redlines on steel wheels and I drove 400 miles to a Regional in 2016 and it drove like a dream at 70MPH. I also ran 30 PSI in the tires no problems at all. I have a set of bolt-ons with black wall radials and the car runs fine with them as well.

Mike

[Paul A.]

Re: Correct Tires

I planned on mounting the bias tires on my repro knock offs. As per the advise above, maybe keep the radials and just get a set of steel wheels for them. All just options at this point. I appreciate all of the concerning posts though.

[Duke W.]

Re: Correct Tires

I don't at all consider bias ply tires "unsafe". In fact they are less prone to tread separations than the typical, cheap S or T speed-rated radials most guys run that lack the safety of a spiral wound nylon cap belt that you find on H and higher speed-rated radials, but many repro bias ply tires are poorly molded and exhibit balance and out of round problems.

By far the best of the repro bias ply tires are Kelsey Goodyears, and if you want to do Flight judging with bias plies the Kelsey Goodyears are the only way to go, and they actually drive pretty well

Take a look at the following thread and then go to the BaT link and look at the driving video, which shows the car being driven in a sporting manner up a "hill climb". The Kelsey 7.75-15 repro Goodyears only deliver about 0.75 max lateral g, but breakaway is very gradual and forgiving, and it was actually fun to steer the front end with the steering wheel and the back end with the throttle. Cold tire pressure was set at 35 psi before the run.

https://www.forums.ncrs.org/showthre...1-Coupe-on-BaT

Also understand that alignment is absolutely critical to stability to these cars, particularly rear toe. When I first drove this C2 it had a severe stability (oversteer) problem turning left. I suspected the right rear toe was OUT rather than in, and once we got it on an alignment track that turned out to be the case. I calculated we needed to swap 3/32" worth of shims from the inside to the outside and it was doable by rearranging the existing shims.

That did the trick... the instability was completely eliminated. We temporarily mounted a set of V-rated 205/70R-15 Avon CR6ZZ DOT legal racing tires on repro 6" rally wheels, and that turned it into a g-machine. The owner who had been a very timid driver with the bias ply tires and rear toe-out problem, which was completely reasonable being as how it seemed possessed by the Devil all of a sudden started driving it with vigor because it was so confidence inspiring.

If you're doing Flight judging mount a set of correct for your year Kelsy Goodyears on the OE wheels and mount a set of the above Avons on a set of repro '67 Rally wheels to enjoy some serious driving fun. They will accept the '63 to '66 OE wheel covers.

Do you know what your alignment setting are? If not, maybe you should find out. Find a shop that has state-of-the-art four wheel alignment equipment and just have them set it up and provide you the current settings. That's it. Don't make any changes. Then figure out what settings you want, touring or sport and what shims you might need to achieve those settings. Then go back to the shop with a supply of OE correct shiims and have them dial it in.

Duke

[Duke W.]

Re: Correct Tires

I think 99 out of 100 chose tires based purely on cosmetic appearance. Do they know that tires are part of the suspension? Probably not, and in fact they are the foundation of the suspension like the foundation of a house.

Always look at the load index, which is a two or three digit number followed by the speed rating letter. It follows the size. The actual maximum recommended load at the maximum recommended COLD tire pressure is also molded into the sidewall in plain English as is the basic construction. DOT regulations require this important data to be molded into the sidewall. If the manufacturer doesn't include this data in their advertising copy or technical specs, shop elsewhere.

Low speed rated radials are typically as follows:

sidewall: two rayon (or polyester) plies; tread: two rayon (or polyester), two steel plies.

H or above:

sidewall: two rayon (or polyester or even nylon) plies, tread: two rayon (or polyester or nylon), two steel, one (or two) nylon plies

Nylon is stronger than rayon and pound for pound stronger than steel, and the nylon cap belt is spirally would around the tread... no butt joints. It's this belt that will in most cases keep a tire from disintegrating if there is an internal failure. Without this belt, the tire may suddenly disintegrate, causing damage to the car and/or loss of control, which can cause a wreck with injury or even death.

These basic specs are certainly not rocket science and you should always look at them at least in addition to cosmetic appearance if not a setting a minimum construction architecture and speed rating.

Most H and above speed rated tires in sizes that are approximately the same revs/mile as OE tires and not too wide for OE wheels are blackwalls. Blackwalls were standard on all vintage Corvettes, and IMO they are best suited for vintage sports cars. ...ever see a vintage Ferrari or Porsche with whitewalls? ...I didn't think so.

Of course you can throw away several hundred dollars to have Diamondback put on your desired sidewall treatment. It's your money.

Oh, and high speed rated tires with the spiral wound nylon cap belt don't "time out" at six years, or whatever you've "heard" on the misinformation network. I've got vintage cars with 30 year old high speed rated tires... no visible cracks... other than some tread wear they look new, but admittedly, I don't drive them on freeways and they rarely exceed 45 MPH nowadays on surface streets, and of course, they rarely see UV light or ozone, which are tires' worst enemies.

Duke

[Paul A.]

[Bill M.]

Re: Correct Tires

Paul i have a 65 that i drove with bias ply tires for 20 years. I have a 67 with radials. Both ride great but different. I find that the biased ply tires do not like crappy roads which are all over New York. I just switched my 65 to radials. The gold line biased ply tires that i took off the car have many miles left on them. They will probably sit around in my garage until i die,so if you want them come and get them.

[Paul A.]