Another C2 Tire question

[Doug L.]

Hi everyone,
It's time to buy the new tires for my '64. I have a set of repro 6.70 x 15s that will be mounted on the correct wheels for judging. Currently on the car is a set of four bias ply F78-15s on non-correct welded, steel, non-tapered rims that I'm guessing may be "8080" rims. Until I dismount the F78s I dont know what the rim width is.

My plan is to buy 4 radials for driving and mount them on the incorrect rims and only put the repro 6.70 x 15s on for judging.

I want to use a US brand radial like Firestone 500 or Goodyear, but the brand is not my problem. The Firestone is available in 215-70R15. I have read on the TDB that 205-70 is a better choice and a cross reference chart I have indicates that 195R15 is also a suitable replacement for the 6.70 x 15.

My concern is that when I raise the rear of the car by placing a floor jack under the differential the rear tires rub against the rubber buffer that is mounted under the arch of the frame rails. When the car has its weight on the tires the fattest part of the inner sidewall is VERY close to that buffer, like within 1/8 inch. This makes me think that I should buy the narrowest tire available or certainly something that is less than 7.8" wide. The 6.70 is 6.7 inches wide at the sidewall. The F78 is presumably 7.8" wide. The 205 is 8.07". The 215 is 8.46". This makes me believe that neither the 205 or the 215 will work due to lack of clearance. The problem could be the wheels not having enough off-set, but I have those wheels and don't really feel like buying a third set.

I found that Goodyear has their "Eagle" in 195-55R15. That would seem to be the narrowest tire available and would get me below the width of the F78s (7.67") but the aspect ratio (height) is only 4.22" verses approximately 6" for the 205 and 215.

Has anyone used 195/55 tires and if so is the appearance wrongon a Corvette? Does anyone have a perspective on this that they could share?
Thanks-Doug

[Alan D.]

Re: Another C2 Tire question

Doug,
For street tires I like the P205X65 R15 which I'm running on the front with P225X70 R15 on the rear Rears are a little large and if given the chance I would go down a size or make the same as front. Neither hit!

The biggest advantage I have is the limited milage the car is used so I do not care about speedo.

[John H.]

Re: Another C2 Tire question

When the car has its weight on the tires the fattest part of the inner sidewall is VERY close to that buffer, like within 1/8 inch. The problem could be the wheels not having enough off-set, but I have those wheels and don't really feel like buying a third set.

Doug -

You're going to have that problem until you get wheels that have the correct offset. Midyears are extremely intolerant of any wheel with non-stock rim width and offset, as they were designed in 1960 around 6.70-15 tires on 5-1/2" rims. Drum brakes give you more wheel choices, as the rim cross-section doesn't have to accomodate the brake calipers, but you want to stay at 6" or less on the rim width with positive offset between .06" and .44". That will give you zero clearance issues with 205/75-15 radials, the most common radial replacement size for 6.70-15 or 7.75-15 tires.

[Doug L.]

Re: Another C2 Tire question

Alan, John,
Thanks for the information. I was afraid that the wheels on the car did not have the correct offset. Once they come off I will measure them and compare with the correct wheels to verify. Original 63-64 wheels are not easy to come by and very expensive if you do. I was able to buy a set of 5 correct wheels for the car but can't afford a second set even if I could locate them. My plan is to mount the repros on the correct rims and have the car judged as soon as the restoration is complete. After judging I will remove the 6.70x15 tires and mount 205 radials on the correct rims.

Thanks again-Doug