Packard Forum Index » V-8 (1955-56)

Yes, another tire thread.

In the past our options were to go with 225/75-15 or 235/75-15, but now that Diamond Back has their bias-ply-look Auburn Deluxe tires I wanted to get some thoughts on sizing with those. '55-56 Seniors had a tire size of 8.00x15. The Auburn Deluxe doesn't have that specific dimension, but does have 8.20x15. Specs for that are:

8.20x15
Height: 29.2"
Tread width: 5.9"
Section width: 8.2"

They also have another size that has similar specs:

7.00x15
Height: 29.4"
Tread width: 5.7"
Section width: 8.0"

I currently have bias ply tires of an unknown age (70's maybe?) in L78-15. Size is about 29" diameter, ~6 tread width, and like 9" section width. They are very hard to get on and off the rear axle. Unsafe to drive, and very discolored with age.

What would be closest to the original 8.00x15? The 8.20 or 7.00? Probably looking at 3.5" or 4" whitewall...maybe. Not sure on beauty bar or not. Was the beauty bar a thing on the 50's cars or was that 30's and 40's?

In addition to the overall size dimensions you might also want to do a bit of research on weight and load ratings on the tires you are considering. I am not sure how important the number is in the big picture with the relatively small amount of driving probably done in our old cars or how it all gets calculated and comes together but Packard typically had sizes in the 700s on the earlier smaller and lighter cars. When the cars got heavier, bigger and in theory could go faster they started going to the 800 sizes.

Doing a quick check on the same brand and type of bias ply tires sold by Coker, the 700-15 has a "Max Load Capacity (lbs)" of 1700 @ 32psi while the 820 number is 1920 @ 32 psi. I would think there would be a rating number available for radial tires too.

Kevin

225 15
Is what I heard, read.

I run the 235, yeah the rears are pitb. To get off.
But do able.

Quote:

Not to sound snippy but why not talk to Diamondback and see what they think? We all know excessive width can be a bit of an issue. A nonstandard OD, not really.

I would hope they could give you the exact dims of an 8.00 vs an 8.20.

Howard - I didn't think about the load capacity. I would assume either load range would be sufficient for our cars, but wouldn't hurt to have a little more. As long as it doesn't make it too stiff.

Riki - I have 225/75 on my '54 Panama. They are fine for that car, but would look undersized on the '56 400. They measure out to about 28" diameter. 235 would be closer to the right diameter, but width is an issue. The benefit of the Auburn Deluxe tires is they are based off the old bias ply sizes, so I can get good diameter and smaller width.

PGH - Not snippy at all, and I'll probably need to call Diamond Back anyways. Looking around on Coker Tire, their 8.00x15 is 29" diameter, 4.7" tread, 8.3" section. So really they are all about the same. Even the same size will likely vary between manufacturers. At least that's what I've found working with tires for my truck. The same size can vary as much as an inch in diameter between different brands and tire models.

I've heard mixed things about the Cokers, and I've had nothing but good things to say about the Diamond Back's on my Panama. So I'll be doing DB again for the 400.

Diamond Back has excellent support and will gladly help with the decision. They helped me pick the proper size for my 1965 Cadillac Fleetwood Sixty Special and even supplied the proper 3-band whitewall needed with a wider band and two narrow ones, one on either side and they are also going to provide the reverse style (two wider with a narrow one between) for my 1965 Imperial LeBaron.

The 53 Caribbean also had originally 8.00-15 Tires, so I went through a similar decision making process. Using the Engine rev/mile specs from the workshop manuals, I calculated that packard originally had a 358mm radius tire. The diamondback 8.20 spec is 371mm (3.6% difference) and coker 8.00 spec is 374mm (4,4% difference). The 8.20 name from Diamondback might better be 8.00.
I went with diamondbacks on the Carib and Cokers on the clipper, but like the diamondbacks better.

I installed a set of the DB 7.00-15 on a customer's junior '51. They performed just great and rode beautifully but to my eye looked a little small for the car. For a senior my vote is for the 8.20.