roadster tire pressure

[Brendan]

I have a 29 Roadster , it has 16 in wheels on it, what is the Minimum air pressure i can run? The tires are Firestone bias-ply , 16,s up front and 16.5 on the rear,

[Gary WA]

35psi

[Marshall V. Daut]

Very often tires will have the recommended pressure embossed on a sidewall near the maker's name or by the raised letters identifying the tire size. But Gary's 35 psi sounds about right. I run Model A pressures between 34 and 36 psi.
Marshall

[nkaminar]

35 psi is a good starting point. Roadsters need less pressure than a heavy sedan. Try reducing or increasing the pressure a little. The object is to have a good pressure patch on the road and not to have the tires get hot. Use your IR temperature gun to measure the temperature. If the pressure is too high and they will wear more in the center and too low they will wear more on the sides. The temperature should be even across the tread and not hot on the sidewalls. Temperature is related to the ambient temperature but not more than 120 F on a 80 degree day after a half hour highway run.

[fourfords]

'29 Roadster, 21" tires. 35 PSI all around. I have a couple V8's, run 40 PSI all around. Slightly better steering.

[henry's 31]

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35 PSI is what Henry wanted.

[CWPASADENA]

28 fronts, 25 rears.

With 16 inch tires, you do not have to run nearly as much pressure. Look at the load rating on the tires and consider the weight of a Model A Roadster.

I have been doing this on Model A and 32 Roadsters for years. Ride much improved, will not wear out the tires. Try it, you will like it.

My experience,
Chris W.

[ronn]

I agree with CW- you asked for minimum...........

[katy]

I've heard of using the "chalk test", but have never tried it:
Copied this off the web:

The chalk test is a method to visually assess if your tires are properly inflated by observing how a chalk line wears off the tread after driving. If the chalk wears evenly across the tire, it indicates proper inflation. If the center wears off more quickly, the tire is overinflated. If the edges wear off first, the tire is underinflated. Exploring Overland
Here's a more detailed explanation:
1. Apply Chalk:
Draw a wide line of chalk across the tire's tread, ensuring it covers the entire tread width.
2. Drive a Short Distance:
Drive the vehicle forward a short distance (e.g., 100-200 feet) on a paved surface, preferably in a straight line.
3. Inspect the Wear Pattern:
Observe how the chalk has worn off.
Even Wear: The entire chalk line should be visible on the ground, indicating proper tire pressure.
Center Wear: If only the center of the chalk line is worn, the tire is overinflated.
Edge Wear: If the edges of the chalk line are worn but the center isn't, the tire is underinflated.
4. Adjust and Repeat:
If the tire is over or underinflated, adjust the tire pressure accordingly and repeat the test until you achieve even wear.

[nkaminar]

The chalk line that Katy talks about seems like a good test. The IR temperature probe that I talked about in Post #4 is essentially the same test. The tread temperature should be the same across the tread after a run on a highway. I am not sure how the temperature profile would be effected but guess that an over inflated tire would be hotter in the center. On race cars the temperature profile is used to set up the caster. After a series of hard cornering the profile is taken and the caster adjusted for uniform temperature across the tread.

[CWPASADENA]

Originally Posted by nkaminar

The chalk line that Katy talks about seems like a good test. The IR temperature probe that I talked about in Post #4 is essentially the same test. The tread temperature should be the same across the tread after a run on a highway. I am not sure how the temperature profile would be effected but guess that an over inflated tire would be hotter in the center. On race cars the temperature profile is used to set up the caster. After a series of hard cornering the profile is taken and the caster adjusted for uniform temperature across the tread.

Yes, we do use tire temperature to help set up a road race car but we had to take the tire temps immediately after coming off the track. If we went back to the pits, the tires would cool enough to lose the information we were looking for. We also used a lot softer compound rubber which would generate more heat when driven hard.
I do not think a Model A on hard street compound rubber would ever generate enough heat to get any kind of a temperature profile to be of much help.
I would think the "chalk" method may yield better information.

My experience,
Chris W.