68 rally wheel rim sizes

[Harry S.]

I have a 68 coupe with aftermarket rims, not corvette, and want to install a set of rally wheels. The tires on the car are pretty new Firestone 225/70R15. I see that there are 15x7 rims and 15x8 rims available and I need to know which one I can use. I believe that the 68 used 15x7 rims but I am not sure if the 225/70R15 are the right tire for that rim.

[Carl N.]

Re: 68 rally wheel rim sizes

Check out a tire mfg web site such as BF Goodrich. They will have a chart showing rim width required for tire sizes. I think 15x7 is correct for a '68, but could be wrong some of the C3 guys should respond soon.

[Joe L.]

Re: 68 rally wheel rim sizes

I have a 68 coupe with aftermarket rims, not corvette, and want to install a set of rally wheels. The tires on the car are pretty new Firestone 225/70R15. I see that there are 15x7 rims and 15x8 rims available and I need to know which one I can use. I believe that the 68 used 15x7 rims but I am not sure if the 225/70R15 are the right tire for that rim.

Harry-------

All 1968 Corvettes originally used 15 X 7 wheels. However, you could use the 1969-82 15 X 8 wheels if you wish.

You can use the 225-70R15 tire size with the 15 X 7 wheels. In fact, most tire manufacturers specify this as the replacement size for the F-70-15 tires originally used for your application. Other references say the 215-70R15 is the replacement size. The 15 X 7 wheels can be used with either size tire.

Either way, you're going to find that there are few acceptable tire choices currently available. As far as true hi performance tires (i.e. "H" or above rating), you will find ZERO.

[Harry S.]

Re: 68 rally wheel rim sizes

Thanks for that info Joe, I will go with the 15x7 rims then to be more correct in the restoration.

[Dan A.]

Re: 68 rally wheel rim sizes

15x7 Ralley wheels are very common. Most are passenger car with the code FW by the valve stem hole.

The 1968 Corvette 15x7 Ralley wheel has a different offset, is a one year only wheel unique to Covette and not so common.

It is stamped with the code AG by the valve stem hole.

Due to this offset difference from the passenger cat wheel the '68 Corvette 15x7 uses the same trim ring as the 1968 and later 15x8 Corvette Ralley wheel. The 15x7 trim ring used on the '68 15x7 Corvette Rally wheel leaves a noticeable gap between the inner circumference of the trim ring and the wheel center.

[Paul H.]

Re: 68 rally wheel rim sizes

My 68 has the stock 15X7 rims and I am running 225-70-15 redlines. Nice fit, no rubbing and they look nice.

[Harry S.]

Re: 68 rally wheel rim sizes

perfect. That is the answer I was looking for. Thank yhou

[Paul H.]

Re: 68 rally wheel rim sizes

You're very welcome Harry.

[Duke W.]

Re: 68 rally wheel rim sizes

I have a 68 coupe with aftermarket rims, not corvette, and want to install a set of rally wheels. The tires on the car are pretty new Firestone 225/70R15. I see that there are 15x7 rims and 15x8 rims available and I need to know which one I can use. I believe that the 68 used 15x7 rims but I am not sure if the 225/70R15 are the right tire for that rim.

The '68 Corvette Rally Wheel is unique to Corvette and that specific model year due to the offset, which is -0.28". Other seven inch Rally wheels used on various passenger car model lines have zero, or very close to zero offset. The negative offset on the Corvette seven inch Rally wheel was necessary to provide adequate clearance with the rear spring end. Given the one model year only use only on the Y-body, originals may be tough to come by. I don't know if they are reproduced currently, but make sure what you buy has the correct offset.

There are reports that the zero offset version will fit, but adequate clearance may come down to the individual vehicle, and it is bound to be tight.

The subsequent eight inch Corvette Rally wheel has -0.50" offset for adequate spring clearance, and the standard tire for late C3s is 225/70R-15. The recommended wheel width for this size tire according to most manufacturers' specs is 6 - 8 inches.

I usually recommend the 225/70R-15 for '68s with OE seven inch wheels. This size has greater load capacity and is slightly taller/wider than the exact replacement size for the OE F70-15, which is 215/70R-15. The 225/70's loaded revs per mile figure is 760 - same as the old 6.70-15 from the sixties. The 215/70 is 775 - same as the 7.75-15 and F70-15. However if I could find a H or better rated 215/70, but only a T or less 225/70, I would recommend the 215/70.

I believe if one does a thorough Web search for the 225/70R-15 size you might find a couple that carry a H speed rating, but they are likely a "brand" you've never heard of. Virtually all H and above speed rated tires have a spiral wound nylon cap belt that will prevent the tire from disintegrating if there is an internal structural failure, so it is a significant safety enhancement even if you never exceed the legal speed limit.

BTW, what is the model name and speed rating of your 225/70R-15 Firestone tires? The speed rating is part of the load index, which is molded into the sidewall immediately after the size - two or three digits and a letter that is the speed rating.

Duke