QUESTION
I’m looking for connection between the tire traction (contact surface) and tire wear in function of tire deflection and tire inflation pressure of truck (truck tractors).
I’ve seen some tire specification of a manufacturer, where they give radial deflection versus radial force for a given tire. Based on these curves (nearly lines at 1-2bar), I can measure the deflection of tire at a given load and inflation pressure (for a given rim width), so theoretically to get the proper deflation is not an issue. Also, as I’ve seen, they give the “proper” inflation pressure for given load at given speed, and this “proper” inflation pressure determined by also the deflation, which deflation have to be the same at a given speed.
If I would get the best performance and lifetime of a tire, I should always dynamically change the tire pressure, based on actual speed, and load.
I also have seen some figure about the result of lifetime of overinflated and underinflated tires.
So what would be the function here?
I’ve found, that Schallamach calculated only with “wheel stiffness” in tire wear topic, and according to Kraghelsky and Nepomnyashchi complex formula the tire wear rate is an exponential function of the length of contact area, but these formulas maybe outdated, and also I think they didn’t even consider the wide super singles…
If I use an overinflated tire, it’s lifetime will be decreased due to contact surface shrinking (among others), but can somebody please give me a function for rough estimation?
REPLIES
CapriRacer
My expertise is in Passenger Car and Light Truck tires, but I suspect that Medium Truck tires (the ones commonly used on Over-The-Road trucks) would react very similarly to those. Keep that in mind as I respond.
The relationship between tire traction and tire wear is highly complex - and reading into your post, it appears that you want to be able to calculate an optimum pressure. So a couple of thoughts:
THE most important thing about inflation pressure is load carrying capacity. That’s the thing that should be driving your quest for the proper inflation pressure.
Secondly, the pressure distribution in a tire’s footprint is a function of inflation pressure, but it is also a function of other things beyond the control of the end user. Things like belt angle can affect the pressure distribution - and this is obviously within the control of the tire manufacturer - and while it might make sense for a tire manufacturer to try to match the footprint to the load/inflation combination in common usage, the real goal would be to get a footprint shape that doesn’t change much with load or inflation pressure. Obviously some tires will be better at this than others.
What I am trying to say is that you will not be able to find a formula because there are too many overwhelming variables.
But we do know these things:
- Excessive toe causes rapid wear. It also is a driver for irregular wear.
- Inflation pressure isn’t as strong of a driver of uneven wear as other things.
- Most tire wear occurs in the cornering mode.
- While camber does affect evenness of tire wear, its relationship is multiplied by toe misalignment. That is, a lot of camber doesn’t cause uneven wear by itself, but a combination of camber and toe will.
- As a general rule, increasing inflation pressure results in a better wear rate (stiffer tire) even considering the uneven wear it generates.
- Traction does peak and fall off as pressure is increased, but that exact relationship is subject to the footprint shape. The important thing here is that the curve is fairly flat in the area of normal usage and for practical purposes can be ignored.
- In Passenger Car and Light Truck tires, the maximum load on the tire shouldn’t be more than 85% of the rated load (at the usage pressure)
So I think the answers you are looking for are:
- Inflate the tire such that the max load on the tire is 85% of the rated load at the usage pressure.
- Pay attention to alignment.
- Driving gently is better for tire wear.
And the result will be as good of tire wear with a reasonable amount of traction as you can expect without knowing anything else (such as the vehicle make and model, operating conditions, exact tire make and model, etc.)
SOURCE
https://www.eng-tips.com/viewthread.cfm?qid=364906
Above is a snippet.