MTFCA Forum

I see a recommendation of 27 PSI all around for balloon tires on a runabout in the 1926 Ford Owner's Manual. Does that sound correct?

A century ago, when the Model T manual was published, the majority of roads were dirt with deep ruts and pitted with potholes. Times are different and driving conditions and the quality of modern day tires are much better now, so the tire recommendations of the 1920’s are not necessarily pertinent to 2021 with our paved streets and highways. I always look for the manufacturer’s recommended tire pressure on the side of the tire and use that. My Goodyear 4.50-21 ballon tires say not to inflate over 40 PSI, so, anything up to that is okay. I have always used 32 to 35 PSI in my tires with good results. Not too hard and not too soft. Jim Patrick.

I do have to drive on dirt roads, about 6 miles minimum per excursion. These roads are actually loose coarse crushed rock and are torture on motorcycle and antique type car tires. About all I can do is go slow and avoid the worst spots. In the late 20's, I believe tires were changing from "fabric" contruction to "cord" construction, with the cord being superior. Perhaps Ford made the low-for-the-era recomendation for the "new" cord tires. Regardless, 27 seems on the low side. The car handles well with 35 cold, but I'd rather give up some tire mileage to protect the car body and suspension from hammering on the poor roads. I'm going to split the difference and run 32 cold. These are Lucas 4.40/4.50-21 tires, and there is no information on them as to max pressure or carcass material. They do perform well.

Ford notes tire pressures, for the 4.40x21 tires. Larger size ties can handle more pressure, most times I use 32psi. in 4.50/4.75 x 21s. But smoother riding can be found with a bit less.
Ford mentions to add 2 or 3 more psi.
Note Ford states “to be on the safe side, add a few more lbs. of pressure”

Dan: That's the table I was looking at. I overlooked the +3 lb recommendation. It looks to me like 27 psi is for dealer demonstrator cars to give a smooth ride. For practical service, it looks like 30-32 psi is the way to go. I have a roadster on Ford wire wheels with a starter, generator and battery, but no bumpers.

I have a large lubrication chart that has the Ford trademark on it that states that the balloon tires should be inflated to 32 lbs. That's what I do and I have never had a tire issue.

That sounds reasonable. 27 seems out of step to me. It might work better on sandy roads at low speeds, but for general service, it looks like 32 cold is the ticket for balloon tires.

If you go online to “Lucas 4.40/4.50-21”, you will find the inflation manufacturer’s recommendations to be 35 PSI. When you have questions regarding a product you have, a quick, online search will usually yield the answer(s). Jim Patrick

I get stuff like, "10 best hotels in Lucas 4.40/4.50 X 21" and Hottest deals on Lucas 4.40", and "Shop real estate bargains in Lucas" "Unsold 2021 Silverados deep discounts in Lucas 4/40!" Nationally known lender must liquidate prime properties in Lucas 440! Hurry! Lose weight FAST with new Lucas 4.40"

Have seen tire manufactures list variable pressures based on the vehicle's weight. Interesting ford chart. I found 28 works well in my 27 R/P empty. 32 made for a stiffer ride. Loaded, I run 32-34 lbs.

I'd think 34-35 would be good for a 4 door sedan carrying 5 people. A roadster with 1 person and no accessory load, maybe 30. 27 seems too low to me for anything except a speedster, and would proabbly be too low for a speedy speedster. Lucas site mentions "such as 35 PSI", which is at best a suggestion.

I use 35 lbs. I have gravel road to my house, about 1/4 mile. I always check them when cold. If they are too low, they will flex more and wear out the casings faster. If you drive them a few miles the pressure will change. On the clincher tires I use 60 lbs.
Norm

I used to run my 26 Roadster Pickup at 26psi (easy to remember and calibrated in my gauge) however the Tyres (tires)
were showing under inflation wear. I now run them all at 32psi with no issue
Alan in Western Australia

Allan, that seems to support the idea that 27 is just too low for most conditions, even with a stripper runabout.

Aren't Model As about 500 lbs heavier than a T with a similar body style?