Cougar wheel size

[sjrdcr]

I am in the process of purchasing a 1968 Cougar XR-7, factory equipped with the F code 302 and 4 speed transmission and steel wheels with full wheel covers. The Marti report states that the original equipment tires were E70-14. The spare is missing and I am trying to determine what is the correct wheel width for a replacement. The Ford master parts catalog lists three different widths: 5 inch, 5 1/2 inch and 6 inch. Could anyone tell me which would be correct for my application?

[8F91F]

I’ve been through this exercise myself, though the Marti report for my car indicated that the original tires were 7.35X14-4 Ply Rated White Sidewall Tires. Here are some of the more valuable bits that I learned, which may be a good starting point for your E70s:

A thorough comparison chart: http://www.carbibles.com/vintagetyresizes.html

@http://theamcforum.com/forum/proper-tire-size_topic54804.html

The old [7.35-14 tires ,] had an 82% aspect ratio. That means that the height from the rim to the top of the tire was 82% of the section width (not tread width). If you take 82% of 7.35 inches, you get 6.03. Double that (because there is also 6.03 inches from the rim to the bottom side of the tire) and you get 12.06 inches. Add 12.06 to a 14 inch rim, and you get an overall diameter of 26.06 inches.

Converting to a modern millimeter designation, your 7.35-14 would be a 185/82-14.

To get the same diameter in a 75 aspect tire, you need either a 195/75 or a 205/75-14. Theoretically, that will give you a diameter of either 25.5 or 26.2 inches. Check with the manufacturer on exact diameter, as not all are exactly 75%, or exactly 195 or 205 mm section width. Look for a 26 inch diameter tire in a 14 inch size.

After considerable other research, I developed a spreadsheet to compare modern sizes relative to the 7.35-14. It can be downloaded in PDF format HERE. My goal was to stay as close to the original diameter as possible, so that the speedometer would be close to accurate without necessitating a transmission speedometer gear change.

The stock wheels are six inches wide.

Hope this helps.

[68gurney]

I believe it should be a 14x6 steel wheel.

http://www2.cougarpartscatalog.com/c8zz-1007-d.html

[xr7g428]

For a '68 You will need the 6 inch wheel to clear front disc brakes if you have those. The '67 used different front discs so you could use the narrower 5.5" wheels on those.