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-   1961 To 1963 Bulletbirds, Rocketbirds - General Technical Discussion (http://squarebirds.org/vbulletin/forumdisplay.php?f=24)
-   -   Tire & Wheel Conversion Size (http://squarebirds.org/vbulletin/showthread.php?t=20558)

GeoffInCarlsbad 05-29-2016 10:22 PM

Tire & Wheel Conversion Size
Hi folks:

Just getting back after health issues.

Looking to source steel wheels for my 1961 T-Bird Convertible.

Shop Manual indicates: 8.00 x 14-4 size tires.

I measured the original hub caps and they are 14" so, I just want to validate the OEM wheels were 14". What's the proper width of the wheel?

I will check with Coker for closest tire size, but does anyone else have any suggestions for getting original-looking tires and what their experiences have been?



dgs 05-30-2016 08:59 AM

Squarebirds also came with the same 8.00-14 tires. They are tall and skinny, unlike modern tires which are short and fat. The best match in radials are 215/75R14 or 225/75R14 and that's what most Squarebird owners are running. Both are going to be a bit shorter and a bit wider, however.

According to Coker:
the 8.00-14s are 7.7" wide & 27.59" tall

The modern sizes can be calculated[1], although there is some variation:
the 215/75R14s are 8.46" wide & 26.69" tall
the 225/75R14s are 8.85" wide & 27.28" tall

I hope that helps

[1] - the first number is the width in millimeters, the second number is the sidewall height as a percentage of the width and the third is the wheel diameter in inches.

So, for 215/75R14:

Width = 215mm/25.4 = 8.46"
Height = 8.46" * .75 * 2 + 14" = 26.69"

del 05-30-2016 10:31 AM

2 Attachment(s)
Here is what the Coker Classic 215/75R size looks like on the car. These were mounted spring 2015 and I'm pleased with them.

bird 60 05-30-2016 07:47 PM

Hi Geoff, good to hear you're back from your health issues.
I have a '60 Bird & the tire size is 225/75R14 Coker Radials with a 2 1/2" Whitewall.
I am very happy with the appearance, handling, & quietness.

Chris....From OZ.

GeoffInCarlsbad 06-01-2016 06:28 PM

Exactly what I Expected
Hi guys:

I only expected the best answers from you all! Thanks. So I guess my last question is:

If I buy 14 inch steelies, is there an issue with width or are they pretty much standard?


DKheld 06-01-2016 09:09 PM

Glad you guys are happy with your Cokers.

Guess compared to bias plys they are acceptable.
I had Bias plys on mine (G78-14) from about 1994-2004. Put Diamond Back Radials on in 2004 - loved them (made by Dayton). Car drove SUPER - almost as good as a modern car and as well as my Ford E-150 van.

Recently replaced the 10 year old Diamond Back radials with Coker Classic radials.

Exact same size - no changes to the suspension, alignment steering etc.

Car is all over the road - I don't like the tires at all. Used to be able to drive with one hand on the wheel and no sawing back and forth. Now I don't feel comfortable driving the interstate at 70mph with 2 hands on the wheel. I've tried different pressures with about 44psi working the best. Wish I had gone back with Diamond Backs..

Just my 2 cents


Sure - they look fine but I would settle for looking worse and driving better.

del 06-02-2016 09:00 AM

Hi Eric,
In my case I was replacing aged bias plys with the Cokers, so yes there was a big improvement in handling. I'm interested in your tire pressure experimenting, though. What pressure are other folks using on the radials? I did notice a bit of the "wandering" effect you mentioned when the tires were first installed last year, but I've either become used to it or it is less now that the tires are broke in.

bird 60 06-02-2016 09:49 AM

36 psi.
Chris.....From OZ.

dgs 06-02-2016 01:14 PM


Originally Posted by GeoffInCarlsbad (Post 101416)
Hi guys:

I only expected the best answers from you all! Thanks. So I guess my last question is:

If I buy 14 inch steelies, is there an issue with width or are they pretty much standard?


A 14" wheel only tells you what the diameter is. They will vary in width & offset, bolt pattern, center hole, etc. The Squarebird wheel, I believe, is 14" x 5.5" wide with a 3/4" offset or 4" backspace with a 5 x 4.5" bolt pattern. I'm not sure if the Bulletbirds used the same wheel dims or not, but with the same tire size they are probably close.

Here's a good image showing what the terms mean. All of these dimensions vary depending on the application.

OX1 06-03-2016 07:02 AM

I recently put these on. http://www.summitracing.com/parts/HKT-10703/

Only a small whitewall, but they drive fine. No wandering, etc...
up to well over 70.

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