Tire wear normal?
 

I have a 2008 f250 and have Goodyear Wrangler AT/S radials 275/65R20. I have always rotated them and they have 50K on them. They still have good tread and are all wearing the same. The issue I see is that they all have more tread on the inside edge than on the outside edge. My question is can this be considered normal wear since normal toe specs are around 1/8 inch toe in. Thanks.