C1 Tire Size

[Christopher R.]

Most of the recommendations for radials for C1s are for the 205/75-15 or 225/70-15 sizes. This is to keep the diameter of the new tire close to the original so that the speedometer reads accurately. The 205/75 is the closest to the original tire. The 225/70 is the more modern bigger tire. The 225/70 minimum rim width exceeds that of the original rims, but I guess that's ignored.

What about 215/70-15? They are listed at 778 or 788 revs/mile. The original 6.70x15 is listed at 760 revs/mile. That's only a few percentage points off.
The 215/70 minimum rim one is the same as the 205/75 one.

When people jump from the closest-to-original-size-205/75 to the 225/70, why is the 215/70 overlooked? It seems like that size would be a good compromise.

I'm trying to give myself more flexibility in tire choice. 205/75 tires are low performance. 225/70 tires look too fat in the wheelwells.

[James F.]

Re: C1 Tire Size

Chris,
I put 215X75X15 radials on 6"modified rims on my '56. After much research I felt they had numbers real close to the rolling diameter of the old 670X15 bias belt tires. They seem to as the speedometer and tach numbers remained as before. The rims were modified to accept the Corvette wheel cover. I'm not recommending 215 here, but reporting that I'm happy with the end result. Regards,

[Duke W.]

Re: C1 Tire Size

A 215/70R-15 is fine. In fact, they are the same revs/mile as the 7.75-15s used from '65

to '67 and will fit Sting Rays without modification of the fender wells on KOs or six-inch

Rally wheels. Those years used the same speedo gearing, so they all read a little higher

than the 6.70-15 shod models.

The only caution that I would add is the the OEM five inch wheels are a bit on the narrow

side for a 215/70. The manufacturer's web sites have tables showing the recommended

widths for each size. Going a half inch narrowed than their range recommends is not

going to cause serious problems, but may reduce the tires cornering grip a bit.

Duke