[timwilky]

Your reading the chart the wrong way round, the higher up the chart, the higher the tensile strength.

However, my concern about being brittle is not its tensile strength. but failure under use. regular shock loading due to the varying loads applied on the axle in use could lead to sudden brittle fracture. you wont know anything until the studs go ping and the wheel falls off. I am not trying to be a doom munger, but I spent 8 years as an R&D engineer in Leylands labs specialising in durability and component failure. I have seen lots of brittle failure caused by design as well as metallurgy.