bias ply vs radial

[sdcat]

I've been reading about the differences between bias ply tires and radials, and there is something I don't understand. They say that bias ply tires tend to roll more on the rims, but require less camber than radials. I would think that if a tire rolled more, you would need more camber. Anyone have an explanation for this?

Thanks,

Justin

[GWise]

This is the best picture I could find to explain. The tire on the left is a bias ply and the tire on the right is a radial. Since the radial tire tends to have a flatter contact patch, in roll it needs more negative camber to keep the contact patch flat whereas the bias ply just tends to utilize the ouside edge of the tire. Does this make sense?

[sdcat]

Thanks, that does make sense!

[slomove]

I think the picture may be somewhat misleading, since my rear 8" (245/50) size ACB10 are very much flat and also wear quite evenly across the surface. I suspect the bias ply rather allows the tires to deform under side load while staying flat footed while the radials may have a tendency to lift the edge? But that is of course just bullshitting without scientific backup.

[GWise]

I think the picture may be somewhat misleading, since my rear 8" (245/50) size ACB10 are very much flat and also wear quite evenly across the surface. I suspect the bias ply rather allows the tires to deform under side load while staying flat footed while the radials may have a tendency to lift the edge? But that is of course just bullshitting without scientific backup.

Gert,

I think that picture is misleading because it's embellished for effect. It's not that bias ply tires aren't flat - but under load and because of their construction the contact patch looks similar to what is shown. I never said they wouldn't wear evenly across the surface.

As far as the radial lifting the edge - that's actually opposite. See the first picture and description here:

https://www.rsracing.com/tech-tire.htm

I don't claim to be an expert - I'm just going off first hand experience and theory I've read. Probably one of the best books I've read on the subject of racing tires is Paul Haney's:

http://insideracingtechnology.com/booktiredescrptn.htm