Tires

["Neal Herman" <chrycordoba@xxxxxxxxxxxxxx>]

While I'm certainly no expert on tires, the 9.50 X 14 size was used on the old bias ply tires.  14 was the size of the wheel diameter, and sometime in '59 the Imperial went to 15" wheels.  I'm guessing that the 9.50 refers to the width of the tire.

 

Now the tires are sized like 225-75R15, where, working backwards, 15 is the radius of the tire, R means radial, 75 means the ratio of height of tire from road to rim/width of tire; and 225 is the width of the tire (in millimeters?).  On new cars that are designed for handling rather than comfort (and what a misguided notion THAT was!), the "75" ratio would be lower.  For example, my '97 Riviera has 225/60R16 tires (225 millimeters wide, 16" diameter wheels, and the height of the sidewall is 60% of 225, or 135 millimeters.  Believe me, it rides much more harshly than my older cars.

 

Back in the 1970s, the tires sizes changed designations.  I have a 1977 Chrysler owners manual I salvaged out of my long-gone '77  Cordoba, which lists various wheels and tires that could have been put on the cars.  GR78-15 and GR70-15 ("R" meant it was a radial; the absence of "R" meant it wasn't a radial, duh!) were okay on the Cordoba, and HR78-15, JR78-15 and LR78-15 were fine for the NYB and Newport.  The 15 would again designate the wheel size; and I'm supposing the H, J or L would be the equivalent of the current "225" and the "78" would be the ratio.

 

If any of this is incorrect, I apologize, and feel free to accurately explain it.

 

Neal Herman

1959 Imperial Crown (on 235/75R15, 2-7/8" white wall radials)

1965 Pontiac Bonneville (on 215/75R14, 1" white wall radials)

1972 Buick Riviera (on 225/75R15, 1" white wall radials)

1983 Chrysler Cordoba (on 225/75R15, 1-3/8" white wall radials)

1997 Buick Riviera (on 225/60R16, 9mm white wall radials)

 

 

----- Original Message -----

From: Mel Wyshynski

To: mailing-list@xxxxxxxxxxxxxxxx

Sent: 12/20/2003 8:24:08 AM

Subject: IML: Tires

Hello All

 

I note that one of the tire sizes offered for 1959 was 9.50 X 14.

This omits the second number which is the height of the tire as a percentage of the width.

There must have been a standard at that time. I recall something about the number 78 but???

Would someone clarify this for me please.

Thank you.

 

Mel