[CompClassics]

Actually tire manufacturers tire sizes can vary widely as to what is embossed on the sidewall of the tire, it can be bigger or smaller but rarely is it exact dimensionally.

To correct further: AVON CR6ZZ 245/60R15 are 26.7" (not 26.9") tall according to the manufacturer.

This thread was not started as a comparison of tire sizes and which tire manufacturer is more correct than another manufacturer. When it comes down to that there is only personal preference and the tires that came on the original cars and since those tires are no longer available it does not matter which brand you use as none of the available tire manufacturers are "period correct" in any aspect other than they are all black. The same can be said for today's comp 289 Cobra wheel manufacturers, there is not one manufacturer that is producing a wheel that is a 100% copy / replica of the original wheels. If you want to be a builder / owner of a Cobra that is a 100% copy of the original 1960s Cobra than why would you settle for wheels (or anything else on the car) that was not as installed on the original Cobras? On the photo posted above with the four Cobras together the two on the left are in period photos, the two on the right are of a car that looks to have non-original wheel sizes, correct me if I am wrong and tire sizes (unless you only are interested in tire heights and nothing else). If I am correct in my observation than the tire widths on those tires in the photo have a wider footprint than the 1960s originals.
I am trying to point out that unless you have the 1960s original parts you have to make do until you can locate it or somebody reproduces it, hopefully whoever reproduces the part (any) does a 100% faithful reproduction of the original.