hilux steel wheels wearing out on the flange (1 Viewer)

[Tin Tin]

HI all,

We have alot of hilux trucks and noticed the flanges on the "inner side" wear out and end up being concave, sharp and damaging tires.

How can this happen?
We ride offroad 100% of the time, with 245/75R16 mud tires, on 16x7 original steel wheels
See in the picture.

 

[Tin Tin]

I have never heard of anyone having this problem.
is it sand between the wheel and bead?
is it low tire pressure?

why is it more significant on the inner side of the wheel?