Barry's Tire Tech: New Stuff!!

[CapriRacer]

Barry's Tire Tech: Monthly Blog

This is my way of pointing out news that I find interesting. Obviously my orientation is towards tires.

Barry's Tire Tech: Bias vs Radial Tires (New July, 2025)

I wrote this up because I saw a video on the subject and thought I could do a better job. The topic has already proven its worth as there is a post a couple of days later asking this exact question

Barry's Tire Tech: Other Types of Tires (New June, 2025)

I wanted to talk about other areas of tires that I worked in, so I went to the TRA Yearbook and decided to do the whole thing!

Barry's Tire Tech: Rubber Chemistry #2 - Machinery used to process rubber (New Apr, 2025)

Barry's Tire Tech: Rubber Chemistry #1 - Types of Rubber used in Tires (New Mar, 2025)

I'd like to do a more extensive look at rubber chemistry, and the above 2 articles are a start. I need help in this area. If you know of a rubber chemist, please send them my way.

 

[novadude]

Thanks. On the Bias vs radial article....

I know you said you were not going to go into details on Bias/Belted, but I am curious as to what areas are improved with a bias/belted tire vs standard bias ply? As I recall, Goodyear Polyglas, Firestone wide oval, and all of the "high performance" tires of the pre-radial era were bias/belted. I could be wrong, but I seem to remember in the early to mid 80s when tire stores were still selling a selection of non-radial tires for passenger cars, they were ALL bias/belted design. Seems like the reproduction tires for 60s/70s era musclecars are still marketed as bias/belted.

 

[CapriRacer]

Thanks. On the Bias vs radial article....

I know you said you were not going to go into details on Bias/Belted, but I am curious as to what areas are improved with a bias/belted tire vs standard bias ply? As I recall, Goodyear Polyglas, Firestone wide oval, and all of the "high performance" tires of the pre-radial era were bias/belted. I could be wrong, but I seem to remember in the early to mid 80s when tire stores were still selling a selection of non-radial tires for passenger cars, they were ALL bias/belted design. Seems like the reproduction tires for 60s/70s era musclecars are still marketed as bias/belted.

Bias Belted Performance? If you reread the article, everywhere the belt is mentioned, that's where the BB tire gets the same improvement - just less so. That's because BB tires are built with angles on the belt closer to the plies, so they can be built on the old bias equipment.

And thinking about it, maybe I should modify the article to include such a comment.

And to the history, there was a time where tire manufacturers tried to use the old equipment and made BB tires, because they could. If there is money to be made, they were all over it!!

 

[novadude]

Thanks. I re-read the article, and from your comments above, my takeaway is that the belt in a bias/belted tire helped deliver longer tread life, and better traction due to the stiffening belt vs a non-belted bias-ply.

From your comments about low aspect ratio being harder to manufacture in a bias tire: Did a stiffening belt on a bias/belted tire help allow a wider tread than would be possible without the belt by providing more support under the tread (thinking about the old L-60s, N-50s, etc)? Does the belt allow for different (more manufacturable) ply angles than would be required without the belt?

 

[CapriRacer]

Thanks. I re-read the article, and from your comments above, my takeaway is that the belt in a bias/belted tire helped deliver longer tread life, and better traction due to the stiffening belt vs a non-belted bias-ply.

From your comments about low aspect ratio being harder to manufacture in a bias tire: Did a stiffening belt on a bias/belted tire help allow a wider tread than would be possible without the belt by providing more support under the tread (thinking about the old L-60s, N-50s, etc)?

No.

Does the belt allow for different (more manufacturable) ply angles than would be required without the belt?

Somewhat. What's going on is this:

A radial ply tries to form a circle. The belt restricts that.

A bias ply tries to form an oval, and the more the angle, the squatter that oval. If I build a BB tire on old bias equipment, the belt restricts the circumference, but not as much as it would if I used radial building equipment.

 

[Hohn]

Thank you for your labors, Barry. The humble site remains the single best repository of tire tech on the internet.

 

[4WD]

No.



Somewhat. What's going on is this:

A radial ply tries to form a circle. The belt restricts that.

A bias ply tries to form an oval, and the more the angle, the squatter that oval. If I build a BB tire on old bias equipment, the belt restricts the circumference, but not as much as it would if I used radial building equipment.

Isn’t the BP method easier to get a stiff sidewall - hence some ST’s are still BP?

 

[CapriRacer]

Isn’t the BP method easier to get a stiff sidewall - hence some ST’s are still BP?

ST tires are very cost sensitive. Making bias tires is a way to use old equipment. That makes the cost very low.

The only time I have heard of a tire being made specifically bias for sidewall stiffness is for racing purposes.

I suspect that the only reason ST tires come in radials is to utilize old radial building equipment. However, segmented molds are expensive and maintenance intensive, so in some respects that still doesn't explain it.

 

[Hohn]

ST tires are very cost sensitive. Making bias tires is a way to use old equipment. That makes the cost very low.

The only time I have heard of a tire being made specifically bias for sidewall stiffness is for racing purposes.

I suspect that the only reason ST tires come in radials is to utilize old radial building equipment. However, segmented molds are expensive and maintenance intensive, so in some respects that still doesn't explain it.

Some dedicated off-road rock crawling tires are intentionally bias ply, because when aired down, the tread has much better conformability to obstacles.