Tyre pressure 1928 Chrysler 72 conv coupe.

[31 LaSalle]

would anybody know the correct tyre pressures for a 1928 Chrysler 72 conv coupe.

fitted with 6.00/6.50x18 firestone deluxe champion gum dipped white walls.

also are these the correct size tyres for this car

thank you

[61polara]

The original tire size for the 1928 Chrysler 72 was 30x6 (18 inch rim with 6 inch sidewalls).  In 1929 the Model 70 used 6.00 x 18.  

[Gunsmoke]

Typically, tires in this era were recommended to have 35-40 lbs pressure, that prevented overheating, and excessive wear. The bias ply tires were less tolerant to flexing than modern day radials which typically run at 30lbs. My 1931 Chrysler CD8 manual says "exactly 40 lbs and measured weekly". Check your manual.

Edited July 23, 2022 by Gunsmoke (see edit history)

[31 LaSalle]

11 minutes ago, Gunsmoke said:

Typically, tires in this era were recommended to have 35-40 lbs pressure, that prevented overheating, and excessive wear. The bias ply tires were less tolerant to flexing than modern day radials which typically run at 30lbs. My 1931 Chrysler CD8 manual says "exactly 40 lbs and measured weekly". Check your manual.

Thank you for you reply I had no idea as to pressures' I will use 35/40 as a bench mark unless I hear otherwise

 

I do not have a manual good job I can access information on this site

I am a member of the pre 50s aac in uk but they do not have a forum

thank you once again

JOHN

[tcslr]

The manual -if you have it - will say. I’d think 40psi front and 35 rear. 

[edinmass]

45 front, 40 rear. Check every week. 

[Vintageben]

3 hours ago, tcslr said:

The manual -if you have it - will say. I’d think 40psi front and 35 rear. 

Yep as per the manual I have for my 72.

[JRA]

I am always learning here. I went to the car manuals to check, and you all are right, tire pressures ranging from 35 to 40 psi, depending of car, or front/rear, except of Studebaker, with 36 at front and 30 psi at the rear.

All manuals define these pressure for balloon tires. 
The current tires available we use in our cars, respecting original sizes/bias, are they classified as balloon tires? Are the air pressure specs of the tires from the past comparable to the ones we should apply in today’s bias ply tires?? 

 

Edited July 24, 2022 by JRA (see edit history)

[JRA]

Just adding some information, checking the tires in my 1920s cars, I can see inscripts in the tire side walls saying “maximum load at 36 psi” for the large cars in my case (6ply), or for my lighter cars (4ply), similar inscript shows 32 psi. All bias ply US made tires.

I have been using 32 psi in my heavier cars, and 28 psi in the lighter ones for a while, based on these tire inscripts, considering I do not use my cars at maximum load, but I am pretty open to change my reference based on knowledge shared here. Thoughts?

Edited July 24, 2022 by JRA (see edit history)

[Flivverking]

My original chrysler info states 35lbs  for open cars and 40 lbs closed with 18 inch rims.

No less no more will do you fine.

[tcslr]

I'll think about this.  I'm inclined to follow the current DESIGN recommendation rather than depend upon the design data of the time ( 90+ years past).  Consider lubricants as an analogy.  There would be LOTS of margin in current design AND then less pressure ( due to lower pressure) on the retaining rings.   

 

Thaks My JRA -I think I just convinced myself.