Air Pressure

[Bert]

 Have Good Year radials on my Avanti. Took it to a car show yestetday and developed a bubble. Let some air out but still hear thimping. What is the correct air pressure for radials on a 63 Avanti? Thank you. 

[lschuc]

If the bubble is on the sidewall, It sounds like the tire has a broken belt and needs to be replaced.  If left on the car, it could result in a blowout.

[studegary]

1 hour ago, lschuc said:

If the bubble is on the sidewall, It sounds like the tire has a broken belt and needs to be replaced.  If left on the car, it could result in a blowout.

A broken belt would give a defect in the tread area and thumping.  A bubble in the sidewall would be a problem, like separation, of the radial plies.  In any case, it is not safe.  Take it to a GoodYear dealer and see if they will warrantee it.

[Bert]

 Tires came with car when I got it 12ish years ago. May have overinflated so need the correct tire pressure. 

[studegary]

48 minutes ago, Bert said:

 Tires came with car when I got it 12ish years ago. May have overinflated so need the correct tire pressure. 

12 year old radials are already overdue for replacement no matter how much tread that they have left. 

[lschuc]

You should really replace your tires.  12 years is much too long to use tires.   With steel belted radial tires, all tire manufacturers recommend replacing tires at least after 6 years, although some say it is safe to wait 8-10 years at most.  The reason is that rubber degrades and can separate from the steel or rayon internal belts. 
Many automakers tell owners to replace tires six years after their production date, regardless of tread life. Tire manufacturers such as Continental and Michelin say a tire can last up to 10 years provided you get annual tire inspections after the fifth year.  
Cracks in a tire's rubber begin to develop over time, appearing on the surface and/or inside the tire as well. This cracking can eventually cause the steel belts in the tread to separate from the rest of the tire. Improper maintenance and heat accelerate the process.

Since you say that your tires have been on your Avanti for at least 12 years, most likely the date code on the tire's sidewall will indicate that your tires are at least several years older.  Over or under inflation can cause rubber degradation or separation from the belts on the inside of the tire, and that is most likely what caused the bubble to appear on your tire.

Please remove your wheels and get your tires replace as soon as possible.  They all me look like they have a lot of tread life left, but underneath the tread, they are an accident waiting to happen. If the tire comes apart on the highway at speed, that can lead to body damage and / or an accident that can injure or kill someone in your car or another car.    

Please do not drive on your old tires!! 

 

See: https://m.tirerack.com/tires/tiretech/techpage.jsp?techid=138

Or:  https://www.edmunds.com/car-maintenance/how-old-and-dangerous-are-your-tires.html

 

 

[Bert]

Appreciate the feedback. Which do you guys prefer on your Avantis. Steel Belted or Bias Ply?

[studegary]

10 hours ago, Bert said:

Appreciate the feedback. Which do you guys prefer on your Avantis. Steel Belted or Bias Ply?

It appears that you need to study up a bit on tire construction.  Steel belted can be radial or bias ply.  Bias Ply can be steel belted or not.  I believe that you are really wanting to know about bias ply vs. radial (ply).  To be correct for your 1963 and for shows, I would say bias ply.  If you are regularly going to drive the Avanti long distances, I would say radial.  

[PackardV8]

JMHO, but bias plys are for show cars and radials are for cars which are driven.   I have run radials since the late 1960s.

Same with air pressures; the recommended 24 front and 20 rear was suicidal, even for the crap bias tires which were OEM.  The high-speed recommendation of 30 PSI was slightly less bad.  With today's radials, it depends upon the size chosen, the wheel width and the manufacturer and how the car will be driven.

jack vines

Edited May 28, 2019 by PackardV8

[mfg]

For what it's worth, I run the Cooper 20575R-15 radials on my '83 Avanti "Everyday Driver" at 32psi front and 30 rear......For a non rack and pinion steering car it seems to handle and ride pretty well at these tire pressures.

[studegary]

4 hours ago, mfg said:

For what it's worth, I run the Cooper 20575R-15 radials on my '83 Avanti "Everyday Driver" at 32psi front and 30 rear......For a non rack and pinion steering car it seems to handle and ride pretty well at these tire pressures.

That sounds pretty good to me.  You could even go with slightly more "offset" such as 33 front and 29 rear.

EDIT:  I am referring to radial construction tires.  

Edited May 29, 2019 by studegary