Original Tires & Rims Used on 1963 & 1964 Cadillacs

[Jason Edge]

 

235/75R15 Radial next to original style 8.2 x 15 Bias Ply

 

The Original Tires & Rims for 1963/64
Below is all of the information I have accumulated over the years regarding tires used, whitewall width, rims, etc.  Source of information includes the Dealer Data Book, Shop Manual, Specification Manual,  Owner’s Manual, and 1^st hand experience in bringing around 50 1963/64 parts cars over the past 2 decades.




Standard Tires & Air Pressure for 1963/64 Cadillacs
- 8.0 x 15", 4 ply Bias Ply, blackwall 26 psi, standard on 60, 62, deVille series body styles

- 8.2 x 15", 4 Ply Bias Ply, whitewall 24 psi,  standard on Eldorado

- 8.2 x 15", 6 Ply Bias Ply, blackwall, 28 psi, standard on 75 series body styles

- 8.9 x 15", 8 Ply Bias Ply, blackwall 24 psi front & 32 psi rear (26 & 40 psi with heavy duty equipment),  standard on commercial chassis body styles

Optional & Air Pressure Tires for 1963/64 Cadillacs
- 8.2 x 15", 4 Ply Bias Ply, whitewall 24 psi, optional on 60, 62, deVille series body styles
                                               
- 8.2 x 15", 6 Ply Bias Ply, whitewall, 28 psi, optional on 75 series body styles

- 8.9 x 15", 8 Ply Bias Ply, whitewall 24 psi front & 32 psi rear (26 & 40 psi with heavy duty equipment),  optional on commercial chassis body styles:

Note: The 1963 Specification Manual (pg 52) and 1964 Specification Manual (pg 30) recommend the 8.20-15 white walls for 60, 62, de Ville body styles with Air Conditioning due to additional weight of air conditioning.

Blackwall vs Whitewall
NOTE: Blackwalls are standard on all body styles except the 6367 Eldorado, however, the majority of 63 & 64 Cadillacs were delivered to the customers with the whitewalls since they were part of the common option groups A, A2, B, B2 in 1963, and 1,2,3,4 in 1964.
 
 

Rims Used:
15" x 6" rim with a 5x5 bolt pattern (5 bolts with 5" bolt circle diameter), painted light dove grey. Rims used on 75 series and commercial chassis cars are the same as those used on 60 and 62 series cars except they are riveted together and are of heavier stock thickness. They are painted light "dove" grey with a daub of black paint around the small mounting hole on the spider section of the wheel.

Weight of Rims:
I had a chance to weigh a 1964 original Standard Rim and 1964 HD 75 series rim and observed the following: 
Standard Rim 22.5 lb, HD 75 series rim 25.5 lb, so it is indeed a heavier stock for the 75 series. 

NOTE: 1961 to 1964 Rims use wider wheel covers than other years!

The 1961 to 1964 Cadillac Rim (Parts Group 2.803 Part # 1476584)  had 16 11/16" 63/64  diameter outer lip where the wheel covers (hubcaps) mount, the 65 and later were smaller diameter with a 16 7/16".  This means a 1961 to 1964 wheel cover is too wide to fit on a 1965 and later rim, and a 1965 and later wheel cover is too small to fit on a 1961 to 1964 rim.

Part Numbers for Rims

Parts Group        Part Number      Year & Body Style             Notes
5.803                     1476586             1961-64 – 75                      Heavy Duty Rims with Rivets
5.803                     1476584             1961-64, exc 75
5.803                     1483457             1965-66 exc 75, CC; 1967 exc Eldo, 75, CC

Example of the standard rim with reproduction BF Goodrich Silvertown tire mounted:



Example of a 1964 75 series HD Rim:

NOTE H stamped next to valve stem:

Note Kelsey Hayes, and 15x16 and 64 (year) markings inside rim:

Tire Manufacturer
Firestone, Goodrich, and U.S. Royal supplied tires. Some literature notes Goodyear as a supplier ,however I have never seen an original looking Goodyear on a 1963 or 1964 Cadillac and they are not listed in the 1963 or 1964 Dealer Data Book.

Note that White Wall widths and distance from rim  varied a bit between brands. 

Whitewall Width & Distance from Rim
Some original literature shows 1963 Cadillacs with whitewalls that appear to be up to 1 1/2" although they also show whitewalls that are clearly 1" to 1.25" in other pictures. From my experience the 1963's tended to be about 1.25".  The 64's tended to be more along the lines of 1" to 1.25". The width and distance from rim also varied a bit between all three tire manufacturers as can be seen between our Firestone, US Royal and BF Goodrich examples below. You also have to consider there was probably old stock with wider tires around that were used on the 63's and 64's.

Looking at our examples by brand below you come up with this chart:
BRAND ...................WW Width ..............Dist from Rim
- Firestone...............1.25”............................... 0.75” (3/4")
- US Royal................1.125” (1 1/8”)................1”
- BF Goodrich..........1.0625 (1 1/16”)..............1.25” (1 1/4")

Example Original Firestone Tire:

In pictures - Note “Pie Crust” shoulder. This is typical of Bias Ply tires and a sought after look for those looking to restore to original.

Original Example Firestone:
A couple of parts cars I have brought in had original 8.2 x 15" Firestone Deluxe Champion spare tires. As seen in picture above the whitewall width is 1.25" and starts about 3/4" off the rim.

Original Example US Royal:
Louis DeMatteo has supplied example pictures of his 8.2 x 15" US Royal with white wall width of 1 1/8 (1.125)" width, and starts about 1" off rim.

Original Example B.F. Goodrich:
Tim Coy has supplied example pictures of his 8.2 x 15" B.F. Goodrich original spare with white wall width of 1 1/16 (1.0625)" width, and starts about 1 1/4" off rim.

What Is the Closest Radial Tire Size?
Many 1963 & 1964 Cadillac owners understandably opt for the road-hugging performance of the radials, so the question comes up "what is the closest radial tire size to the 8.2 x 15 bias ply?" Most agree that the 235/75R15 Radial is closest in size although it is shorter and a wider tire as you see the picture at top of this article. This is why the 235 will not fit over the rear end trunk hump storage compartment for the 4 window sedans and hard top coupes that stored their spare tire in that area. If they made such an animal something like a 225/85/15 would be closer to the original dimensions.

Height Comparison:
For a specific height comparison, the 8.2 x 15 bias ply are often listed as 29.59" tall, and the 235/75/R15 radials at 28.90. That ends up being a 0.69" height difference. This would effectively drop the car height by 0.69"/2 = about .345" or just over 1/3" .

Speedometer effect:
By dividing the diameters we get a 2.4% difference, and since the radial is the shorter of the tires it will make the cars actual speed slower than shown on the speedometer since the for every turn of the driveshaft is travels 2.4% less distance, or 97.6% the distance it would have with the bia ply.   This means if your speedometer was 100% accurate running the 8.2 x 15 bias, then when you are showing 100 mph you are actually traveling 97.6 mph, or at 50 mph you are traveling at 48.8 mph, and so on.
Simply multiply your shown speed by 0.976 to get the actual mph.

Wide Whitewalls on a Radial
Coker Tire, Diamondback Tire, and others make a 235/75/15 radial with the wide whitewalls for those that want the ride of a radial and the retro look of the older tires.

 

Going after the Original Look
If you are shooting for the original look anywhere from 1" to 1.5" is probably ok. Anything over 1.5" is definitely not the original equipment for 1963 & 1964. Conversely, these cars also never came with the smaller ¾" whitewalls that are sometimes available and were so popular into the 1980’s.
 
 

Staying Original
The closest I have found to the original tires has been the BF Goodrich 8.2 x 15 4-ply Silvertowns with the 1" whitewall offered by Coker. For my 64 Coupe DeVille pictured below I am after an original "tall" look and have had excellent driving experience for 20+ years with these tires. No, they don’t give you the "road hugging" performance of the radials, but they are perfect for what I am after.

 

Original BF Goodrich and Goodyear Examples Needed: If anyone has original BF Goodrich or Goodyear tires please take pictures and measurements and send to me at [e-mail]. I would love to document all original tires available in 1963/64.

[Jason Edge]

It was fun discussing. One reason we research and document is to preserve for future reference. I forget half the stuff I post and have to go back to it myself!

 

[Jason Edge]

This page was updated to include additional information I posted in the September 2012 Newsletter.