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There is a nice looking Firestone white side wall that is the equivalent to the F70 X 14 that I was looking at the other day at my local Firestone dealer; very nearly the same tire as an original Firestone Wide Oval WSW as was installed on my 69 XR7 according to the factory invoice but of course with P215/70 R 14 markings and the WSW is closer to the rim that was originally on the vintage 1969 tires.
Check it out. That would be your best bet or you can buy a set of Vintage Reproductions from Diamondback Tires. There has been a thread here on this site recently and some of us are looking into getting a few sets for our cars.
Hope this answers your questions ? and helps.
Take care "catfan"...***********
 

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An F70-14 (bias ply) or FR70-14 (radial ply) equates to the either the ETRTO current tire size system of 215/70R14 or P-metric system of P215/70R14.

P=Passenger car tire
215=215mm inflated tire nominal section width at the widest section of the tire (sidewall)
70=nominal Aspect Ratio (tire section height is 70% of nominal section width)
R=radial construction (the carcass plys are not bias, they (polyester cords) run radial and parallel to each other)
14=rim diameter in inches

What other product line do you see a label with both English SI units and metric dimensions???

http://www.tireguides.com/tip6.html-CIPCZQX01c821acb8=00005200e4dcdcbe00000000
 

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I'm going to disagree on this. The 225/70R14 is a slight bit larger, but a better match to an F70-14. The Coker Wide Ovals are 26.2" tall and my Yokohama Avid S/T's are 26.4". The BFG Radial T/A is a little taller at 26.5". Both of the 215's are too short at 25.9" and 25.8".

http://www.cokertire.com/store/customer/product.php?productid=17357&cat=276&page=1

http://www.tirerack.com/tires/Spec.jsp?make=Yokohama&model=AVID+S/T

http://www.tirerack.com/tires/Spec.jsp?make=BFGoodrich&model=Radial+T/A

I have 225/70R-14 Yokohama Avid ST's on the 71 and they look just right. The 215's would look too small IMHO.

FWIW, you can't directly compare a radial to a bias tire. Contruction is totally different, so the sizes will never equal up. Your only possible reference that will put you close is the tire diameter in your rim size and aspect ratio. I have always used these sizes as a rule of thumb as they most closely match the advertised diameters of the various tires.

E70-14 = 215/70R14
F70-14 = 225/70R14
F60-15 = 245/60R15
 

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Hemikiller said:
I'm going to disagree on this. The 225/70R14 is a slight bit larger, but a better match to an F70-14. The Coker Wide Ovals are 26.2" tall and my Yokohama Avid S/T's are 26.4". The BFG Radial T/A is a little taller at 26.5". Both of the 215's are too short at 25.9" and 25.8".

FWIW, you can't directly compare a radial to a bias tire. Contruction is totally different, so the sizes will never equal up. Your only possible reference that will put you close is the tire diameter in your rim size and aspect ratio. I have always used these sizes as a rule of thumb as they most closely match the advertised diameters of the various tires.

E70-14 = 215/70R14
F70-14 = 225/70R14
F60-15 = 245/60R15
No, there are actually at a minimum 2 considerations when matching a tire size; 1) inflated OD as you mentioned and the other important factor 2) inflated tire section width.

Back to the original question of matching the closest modern size to a F70-14, I stand by the 215/70R14 size and here is why.

Two issues with the 225/70R14 tire. First, the inflated section width of a 215/70R14 tire is slightly wider at 8.7 on a 6.5" wide rim vs the F70-14 when mounted on equal width rims. The F70-14 is around 8.3" in Section Width (SW) and that is measured most likely on a 6.0 wide rim...so add about 0.2 inches to SW for the F70-14 tire mounted on a 6.5 rim making it around 6.5" in SW.

The 225/70R14 dimension mounted on a 6.5" wide rim yields an inflated SW of about 9.0"...add in the slightly larger OD as you mentioned and we have a larger tire in OS and SW.

Second, depending what rim size you currently have the F70-14 tire mounted on dictates the maximum size of nominal section width tire you are allowed to mount. Do you have a 5.5" or a 6.0" wide rim? Here are the "APPROVED RIM" widths from the Tire and Rim Association:

P215/70R14......5.5, 6.0, 6.5, 7.0 inches
P225/70R14......6.0, 6.5, 7.0, 7.5 inches

So, if you have a 5.5 inch rim, you should not mount a 225/70R14 size tire.

Hemikiller, I won't disagree with your statement the 225/70R14 looks better on a Cougar because it does IMO....I'm only disagreeing with your statement that the 225/70R14 matches closer in size to an F70-14 tire because a 215/70R14 is slightly smaller in OD but slightly larger in SW. :beer:
 
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