tires for 1965
I would like to get two sets of tires, one set of large tires for the street and one set of correct repro tires for judging. My tire supplier is recommending 215/65X15 radials for the street and my knowledgeable Corvette mechanic who has a lot of experience racing Vettes is recommending the largest tire (235/60X15) that will fit without damaging the fenders. I plan on mostly easy cruising with occasional sporty driving. I would appreciate any advice on this subject.
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Re: tires for 1965
An "upgrade wheel" that I recommend is a proper repro of the '67 Corvette 6x15", 0.030" offset Rally wheel. It will accept the OE wheelcovers and mount a 215/70R-15 (which matches the revs/mile of the OE 7.75-15, but is wider) without interference on C2s unless something is way out of whack.
If you search The Tire Rack Web site for this size, you will find one that is Z(W) rated that has been installed with very good results by a number of C2 owners.
This tire was OE on a number of Jaguar sedans, and is considered an all-season high performance touring tire, so it provides good handling without ride harshness. Combined with the W speed rating (168 MPH) it should meet the needs of C2 owners who like to drive their Corvettes as they were meant to be driven.
If you need more grip Avon makes a DOT legal racing tire in this size - the CR6ZZ. It's on the Avon web site.
DukeComment
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Re: tires for 1965
Just be careful when you go about trying to source the 'biggest/widest' tire you can get for your street use. One of the common errors made is to ASSUME that all tires in a given class, say 215-70R-15, have the SAME physical dimensions... This is NOT true.
The size ratings simply determine a generic class of tire where the offerings of different manufacturers are 'similar' in geometry. Ask the retailer to pull the manufacturer's spec sheet and quote specific dimensions to you. You should find subtle differences in exact size based on specific manufacturer as well as specific model of tire within a given class/category.
That 'fine print' distinction can make a difference in fit and wheel well + spare tire storage fit/clearance! It can also mean one guy's recommendation of this/that tire for the application fits/works where another tire with different mfgr/model having the same generic classification doesn't fit/work....
Pushing the envelope can bite you if you're not careful to do the homework up front!Comment
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Re: tires for 1965
Jack - The Tire and Rim Association promulgates dimension standards for each tire size, and they occupy a very narrow range for each size, so you will see little variation in mfg's. specs for a given size.
One issue that published specs don't address is shoulder design. Some are "square" and some are more rounded, and typically the higher the aspect ratio, the rounder the shoulder profile. A "squarer" shoulder increases the chance of fender lip interference.
That said I have not heard of any significant clearance issues with 215/70s mounted on dimensionally correct '67 6" Rally wheels.
Excess camber in the positive direction on either end can cause interference with the fender lips, but zero to slighly negative should be okay.
The other issue is shoulder interference with the frame - especially on the steering gear carriage bolt heads, which has been reported. This only happens at full steering lock and is not a safety issue since full lock is only used at parking lot speeds.
DukeComment
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Re: tires for 1965
Thanks for your input. I have decided on mounting either 215/65 or 215/70 tires for street use. I have had good luck in the past with 215/65's but there seems to be preference in our hobby for the 215/70 size. I'm assuming that this is a more correct diameter in the interest of speedometer accuracy?
GeorgeComment
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Re: tires for 1965
The 7.75-15 is speced at 775 revs per mile. Typical 215/70s are speced at this value +/- no more than about 2, and both are typically specified at or very near to 27.0" inflated diameter.
At about 805 revs/mile/26.0" diameter, the 215/65 will add about another 4 percent error on the high side to the typical 1-3 percent high error that is already present. (The C2 speedometer gearing was set up for the 6.70-15 size of 760 revs per mile, so the 7.75-15 size adds about 2 percent, high error.)
Another 2 percent to the high side is added by the time tread depth gets down to the wear bars.
So if you want to fill up the fender wells to the OE look and value speedometer accuracy...
DukeComment
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Re: tires for 1965
I just love all the knowledge that NCRS members are willing to share. Thanks for all your input.
GeorgeComment
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