Re: {Chrysler 300} Tire Pressures

Previous to these, I ran Diamondbacks (6-ply Vredsteins) for 55,000 miles over 10 years. Tread was still great, but outer and inner edges of vulcanized wide whitewalls were lifting after a few years. I was runnng them at 36-38. Spoke to DB’s sales rep, James, about this issue, and he said I was running them too low - saying they s/b run at 44 psi, which I did for the final several years. Other than the applied whitewall issue, I had no problems with their performance over the high miles I’ve driven my F. Bottom line, it depends on the mfr’s recommendations for our applications and, as Dyke Ridgley stated, taking it from there according to the ‘feel’ of our cars.

I’ll be driving my F from Chicago to our Fall Omaha Meet in September. Hope to see many of you with your Letter Cars there! It’s really not that far a roadtrip for many of us, and there’s no better feeling than taking our Brutes cross country out on the open roads, as they were meant to be driven. Kurt Brueske has prepared a wonderful agenda of events for us!

Noel

Sent from my iPhone

On Jul 26, 2024, at 1:23 PM, Carl Bilter <cbilter@xxxxxxxxx> wrote:

DB has consistently recommended "higher end of the range" tire pressures- they told me 38 psi cold, but 40 would be ok (most/all? radial tires max. inflation higher than 40 psi). This applies in particlular to the wide whitewall radials. Radials have more tire sidewall "squat" under load than bias ply - and higher pressure improves the "look" of the tire under load as well as helps protect the wide whitewall from damage.

American Classic by Coker used to recommend 35 psi.

Even when our cars were new, the road test reviewers often increased tire pressures over the ulta-low 22 or so psi specified by the factory, resulting in greatly improved handling.
I think the low psi was specified to provide the "soft, comfortable ride" that was marketed back in the day.

Carl B.

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

From "'John Lazenby' via Chrysler 300 Club International" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>

To "Nick Taylor" <nicksgaragesd@xxxxxxxxx>; "James Douglas" <jdd@xxxxxxxxxx>

Cc "Chrysler 300 List Server (chrysler-300-club-international@xxxxxxxxxxxxxxxx)" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>

Date 7/26/2024 12:33:26 PM

Subject Re: {Chrysler 300} Tire Pressures

I have four sets of DB radials. Two Chrysler station wagons and two Letter Cars. As per DB direction and also my tire shop, Performance Plus Tires in Long Beach, CA they recommend 40 PSI which works well for me. I've tried lower settings but the cars feel mushy. When I ran L78x15 bias I used 35 PSI and once again lower the cars felt mushy. Our '57 300C is still on bias tires but waiting to upgrade.

John Lazenby

On Friday, July 26, 2024 at 09:40:56 AM PDT, 'James Douglas' via Chrysler 300 Club International <chrysler-300-club-international@xxxxxxxxxxxxxxxx> wrote:

I have run tires all over the place in the last 30 years on my classic cars. I would love to come up with a more science based way to figure it out.

I did run across this but have no way of knowing if it reflects reality or not.

https://www.engineersedge.com/calculators/tire_pressure_vs_load_16251.htm

According to this a 4000 pound 300K should be running about 28.9 PSI for a tire with a 1764 max load rating at 51 PSI.

James

From: Nick Taylor <nicksgaragesd@xxxxxxxxx>
Sent: Friday, July 26, 2024 09:27
To: James Douglas <jdd@xxxxxxxxxx>
Cc: Chrysler 300 List Server (chrysler-300-club-international@xxxxxxxxxxxxxxxx) <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Subject: Re: {Chrysler 300} Tire Pressures

I've been running radials on old mopars since I first switched over on my 1964 300 back in the late 70s. I pretty much run them at 32 psi on everything. My 300F has American Classics and Coker Classics before that and it seems to be the best pressure. Certainly couldn't run the 22 psi that the original bias tires were run at.

Nick

On Fri, Jul 26, 2024 at 9:17 AM 'James Douglas' via Chrysler 300 Club International <chrysler-300-club-international@xxxxxxxxxxxxxxxx> wrote:

I am sure this will open up a pandoras box…

I would like to know how people are dealing with the subject of tire pressures with modern radials on those older Chryslers?

The Service Manual pressures for bias ply are obviously way too low. So, how are people arriving at a “proper” tire pressure for optimum use and tread life?

It would be nice if the tire companies put on their websites the load-pressure graphs they no doubt have. But of course, they will not.

If one runs at the max pressure on the tires and the car is substantially less in weight, then the tires will not perform as well or wear as well as the should. Same if they are under inflated.

So, I would like to hear how people are dealing with this issue.

Thanks, James