What Size Tire Replaces an F78-15?

by Tim Plaehn

Alphanumeric tire sizes such as F78-14 were used in the 1970s before the widespread use of radial tires. The typical tire from that era had a tall, narrow profile, and replacement tires should have similar dimensions.


An F78-15 tire has a nominal diameter of 27.2 inches. The 78 aspect ratio indicates the tire would have a maximum width of 7.75 inches. The tire would fit on a rim that was 15 inches in diameter and 5.5 inches wide.


The metric tire sizes that are closest to F78-15 are 195/80-15 or 205/75-15. A 205/75 tire has a diameter of 27.1 inches and a width of 8 inches. The 80 series tire sizes are not commonly found.


F78-15 tires were of bias-ply construction. Tires in a 205/75-15 size will be easier to find as radial tires. Radial and bias ply tires should not be mixed on the same vehicle. If a wider tire is desired, 215/70R15 or 235/60R15 will provide the same diameter, but wider wheels will be required.

About the Author

Tim Plaehn has been writing financial, investment and trading articles and blogs since 2007. His work has appeared online at Seeking Alpha, Marketwatch.com and various other websites. Plaehn has a bachelor's degree in mathematics from the U.S. Air Force Academy.

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