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Old Guy Question: Vintage 4 ply tire pressure

2K views 6 replies 5 participants last post by  xntrik 
#1 · (Edited)
Here is a question for you older Rodders:

I am running BFG Silvertown 4-ply's on my steel '27 Ford Roadster Pickup. 820-15 w/ 15x8 rims on back, 500-15 w/ 15x4 rims on the front. The RPU weighs in at 2250 lbs. (SBF, 4-speed, 9 inch rear, yadda, yadda,yadda)

I am running about 30 psi in all four tires. Any problems dropping the air pressure? Will this make "flat spotting" worse?

Hopefully I can get some "actual, yeah I know 'cause I have tried it" replies to this question, as opposed to the standard "put radials on it" no brainer responses.

Thanks in advance Ya'll.
 

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#3 ·
I would get myself a very good accurate tire pressure gauge and try dropping to say 27 or 28 lbs on those tires..a pound or two makes a real difference with bias ply..if you go down to 20 or so you may run into issues with heat and handling as well as flat spots..Now what that is is a trick from the racing days when we woudl adjust tire pressures to get the best handling..30 lbs on those tires and that car sounds like a good place to be tho to me..

Good luck..

Sam
 
#4 ·
As a older guy ... Been there tried that ... bias ply deal ...

Start at 30 lbs and just experiment ...
My 32 would NEVER get the ride I wanted with the bias ply tires. I started with radials ( and was spoiled by the good ride ) and then tried the bias ply ... for looks . Bad idea on my part ... Went back to the radials ...

Deuce Moderator ... :D
 
#5 · (Edited)
lakeroadster said:
Here is a question for you older Rodders:

......Any problems dropping the air pressure? Will this make "flat spotting" worse?

Hopefully I can get some "actual, yeah I know 'cause I have tried it" replies to this question, as opposed to the standard "put radials on it" no brainer responses.

Thanks in advance Ya'll.

OK, I grew up with this stuff and watched the transition from nylon cord to polyester cord and then to belted and on to radial tires.

Tires flat spotting when parked is a characteristic of bias ply tires, worse for nylon cord than for polyester cord. Changing pressure makes little to no difference, except to say, less pressure is worse. They will bump until warmed up.

High speed driving and then parking, especially on a very cold day, adds to the severity of the bump.

I have seen some "made in the 2000s" radials do it when parked for weeks.
 
#6 ·
xntrik is exactly right......the reason I run 35 psi in all my tires radial or bias is because if I don't they wear on the outside edges. I have found with 35 they wear even. Another thing letting radials sit up for sevearal days or a week at a time will cause flat spots and instead of coming back into shape like a bias tire does they will eventually slip the belts if you do it enough. I just replaced all four tires on my Z-71 on account of that....I only drove it on weekends for the past three years. The folks at the tire shop said that will make them slip the belts or separate the belts. It made it drive bad and had a funny wear pattern.
 
#7 · (Edited)
Henry Highrise said:
xntrik is exactly right......the reason I run 35 psi in all my tires radial or bias is because if I don't they wear on the outside edges. I have found with 35 they wear even. Another thing letting radials sit up for sevearal days or a week at a time will cause flat spots and instead of coming back into shape like a bias tire does they will eventually slip the belts if you do it enough. I just replaced all four tires on my Z-71 on account of that....I only drove it on weekends for the past three years. The folks at the tire shop said that will make them slip the belts or separate the belts. It made it drive bad and had a funny wear pattern.

Yep, :welcome: had TAs and Eagles do it. But it is a pain to jack it up when parking.

Never saw any Michelin do it or the old TAs that are now being repopped with the wide whites.

www.readershotrods.com
 
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