Re: {Chrysler 300} The Never Ending Tire Saga for 14 inch wheels and tires (300K)

[EM-ATC-2021 <millserat@xxxxxxxxxxxxx>]

The HR78-14 Diamondbacks are equivalent to the original 8.55-14 while the 215/75R14 are equivalent to the smaller 8.25-14 (original 8.00-14). Bottom line the 215/75R14 are slightly undersize to replace 8.50-14 which I believe would have been OE on a 300K while the HR78-14 would be "correct" replacement size.

Having said that, I will admit to running the Hankook 215/75R14 on a 67 Newport for the same reason$ with no problems and I would note the 215/75R14 were rated at higher pressure and more than sufficient load capacity at reasonable pressures.

The OE 8.50-14 would have been rated at 1265 lb at 24 psi - though most of us ran them at 32 psi and subsequent load tables for the 8.55-14 recognized higher load capacity (1770 lb at 32 psi). The 215/75R14 Hankook are rated at 1664 lb at 35 psi.

In each case, the profiles are different from OE tires which would have been width = 83% of section height (a nominal figure not much enforced at the time - but it means the original tires were taller and more narrow).

The HR78 would be 78% and the 215/75 would be 75%. Furthermore, radials have more "squat" so the net result will be the car sits lower regardless of your choice - just a matter of how much lower you will accept).

8.50-14 data from 1962 BFG Engineering Data shows 28.3 in OD, 7.86 sidewall width on a 5.5 inch rim, 4.73 tread width and significantly a 13.07 in static loaded radius (height from ground to center of wheel mounted on car).

HR78-14 Michelin XWW data (for what appears to be nearly identical to the Diamondback tire) is 27.5 in OD, 8.9 section width on 6 in wheel, and 12.0 static loaded radius. So you have already lost an inch of car height / ground clearance - but note these would have been the "lower profile" tires directly replacing the 8.50-14 in the mid 1970's.

215/75R14 Hankook data shows a 26.7 in OD, 8.5 in section width on 6 in rim, 5.3 tread width, but no static loaded radius data - though one could infer it would be roughly 0.4 less than the HR78-14 based on 0.8 difference in overall diameter. So lets guess 11.6 in.

But realizing the trend was to lower profile tires in the 70's and accepting the 12 in Static radius, is another 0.4 in going to bother you? As to the quality and durability of the Hankooks I would not hesitate to go that way.

Hope that helps. Best, Ed

On 10/10/2022 11:07 AM, 'James Douglas' via Chrysler 300 Club International wrote:

So,

 

It appears that the Wheel Vintiques 14 inch wheel I ordered as a test will work with the stock 300K hub cap. The only issue is the valve stem hole is a little off. I tend to favor brass stems which do not bend at all. Rubber stems will bend just a little and would work. In my case , I think one of the angled valve stems will solve that issue and get the best of both worlds. I also like the brass ones as they act as a hubcap rotation stop without cutting into the rubber stems.

 

Now to tires. We plan is driving this car daily. I have DB tires on my other classic cars, but they do not get many miles on them. I hate the idea of driving on $300 tires regularly. I went looking for a substitute and I found the following the following information. By comparison, I am showing the DB Auburn.

 

Auburn……………… HR-78-14…………..Height = 27.5……….Tread Width = 5.5……….Section Width = 8.3……….Load = 1764

 

HanKook ………….215/75R14………….Height = 26.6……….Tread Width = 5.9………..Section Width = 8.4……….Load = 1764

 

Other then the height being 29/32 shorter ( 1 inch) the tires are basically identical.  These Hankook tires are $110 delivered. The Auburn’s would be $300 each delivered.

 

Anyone have any experience with this tire?

 

Thanks, James

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